How the British and American Political Systems Are Trading Places

LONDON — When the British House of Commons denied Prime Minister David Cameron authority last August to bomb Syria, the uprising was even more stunning than the simultaneous rebellion against President Obama over the same issue in Congress. While legislative defeats are relatively common for American presidents, the British system usually provides so much leverage to its prime ministers that the position has been described as an "elect­- ive dictatorship."

The British vote on Syria was a flat rejection of Middle East intervention and a rebuke to 10 Downing Street. But it was also something more: evidence of a trend toward the splintering of political influence in the nation that has provided the world perhaps its preeminent model of a parliamentary system that concentrates power in the hands of a single governing party.

That consolidation of power, which for generations has defined the British political system, is under siege from a convergence of factors that include dwindling voter loyalty to the two major alternatives; diminishing party discipline inside Parliament; and the rising probability that no single party will win enough seats to control the Commons without forging a multiparty coalition. "For a long time, we were a strong, centralized, executive state," says Peter Riddell, director of the London-based Institute for Government, an independent think tank. "Now you are talking about a much more "¦ unpredictable electoral structure." Prime Minister David Cameron, Deputy Prime Minister Nick Clegg and Labour Leader Ed Miliband are featured on Politico Top Trumps cards. (Christopher Furlong/Getty Images)

From the outset, those decentralizing forces have shaped Cameron's tenure as prime minister. In 2010, voters ousted the Labor Party, which had controlled the government since 1997, but the electorate did not provide enough seats to Cameron's Conservatives for an outright majority in the Commons. That forced Cameron to negotiate a governing agreement with the Liberal Democrats, Britain's eclectic, centrist third party, and to form Britain's first peacetime coalition government since the Depression.

Overall, observers and participants alike say the coalition has held together better than most expected, particularly on the core fiscal choices the partners faced. But enough differences have opened between them — and, even more important, between Cameron and his party's conservative vanguard — that British political scientists say this session of Parliament is on track to produce the most legislative rebellions within the ruling government since World War II.

And while the British electorate over the past century has only rarely denied one party an absolute majority, many here believe it may become more the rule than the exception. Voters are increasingly drifting away from the two principal parties toward alternatives such as the UK Independence Party, which has shown increasing strength behind an agenda centered on nativism, isolationism, and cultural conservatism. "We may find we are in an age where we don't [generate] majority governments in a system that was always designed to produce clear outcomes," says Graham Brady, a Conservative MP.

All of these intersecting developments are signs that in the basic operation of their political systems, the United States and the United Kingdom may be trading places. Even as the American system is growing more rigid and centralized, Britain's is becoming more fluid and fragmented. The U.S. constitutional structure, designed to encourage compromise, is increasingly generating only stalemate and conflict; meanwhile, the British system, designed to produce decisive outcomes and unwavering direction, is now demanding more compromise and negotiation, both within and among the parties.

Put another way, while the U.S. is acquiring more of the characteristics of a classic parliamentary system, Britain may be shedding some of them. "The picture of British politics with which you and I both grew up needs to be retouched or even redrawn," says Anthony King, a University of Essex professor of government and a leading student of Britain's system.

For most of American history, the U.S. political system has been defined by weak, ideologically diverse parties that only lightly held together a wide range of competing views and contesting camps. In Congress, for generations, the divisions within the parties — say, between segregationist Southern Democrats and the Northern liberals promoting integration, or between Republicans who held isolationist and interventionist views on foreign affairs — were as pointed as the differences between them. When Richard Russell and Hubert Humphrey were both Senate Democrats, and Jesse Helms and Jacob Javits were both Senate Republicans, party discipline was a contradiction in terms, and accomplishing anything in Washington required an enormous amount of bargaining.

But since the 1960s, both parties have experienced a geographic, cultural, and racial "great sorting out" that has left each side's electoral coalition much more ideologically homogenous (especially the GOP's). In Congress, party-line voting has soared, and the number of ideological outliers — moderate Republicans or conservative Democrats — has dwindled. At the ballot box, split-ticket voting has fallen, as more Americans vote a straight party line in presidential and congressional races.

The result is a political system that many observers have described as increasingly parliamentary, defined by an unrelenting competition between two parties that have grown more antagonistic and centrally controlled even as their competing visions for the country have become more antithetical. This has produced an environment of implacable confrontation, in which Washington has struggled to reach consensus even on issues long considered less partisan, such as agriculture policy.

Across the Atlantic, the United Kingdom is moving in the opposite direction. For most of its modern history, it provided the world's preeminent model of a tightly controlled parliamentary system. As one British political scientist wrote in 2011, "The [British] model is recognized the world over as delivering strong, stable one-party government." One key to that model has been a legal structure that provides control of the executive branch to the party that holds the majority in the House of Commons. A second has been a political culture that has delivered lockstep levels of party discipline inside that legislature. The third has been an electoral system that, since the turn of the 20th century, has almost always provided one of the two major parties — Labor on the left and the Conservatives on the right — enough seats in peacetime to control a Commons majority and form a government without needing to negotiate a coalition with smaller parties, much less each other.

This convergence of factors has afforded British prime ministers as different as Margaret Thatcher and Tony Blair almost untrammeled freedom to implement their agendas without effective opposition. That tendency has inspired the description of Britain's system as an elective dictatorship, not to mention the wistful jealousy of American presidents confronting a constitutional structure that presents them with trapdoors at almost every turn. One measure of how much leverage the system has traditionally afforded the prime minister is that Cameron's loss on Syria represented the most consequential Commons defeat for a British PM on an issue of war and peace since 1782, when weary British parliamentarians rejected Lord North's request to continue fighting the American Revolution after the defeat at Yorktown.

But like waves against a seawall, big changes in British politics and life are crashing against that fortress of centralized authority. The longest-developing of these changes is the declining electoral dominance of the two major parties.

In 1951, the Labor and Conservative parties won a combined 97 percent of the votes cast in the parliamentary election. That dropped to just below 90 percent by the 1960s, and to around 70 to 75 percent in most of the elections from the 1970s through the 1990s. Their combined share fell again to about two-thirds in the 2005 election, when the Labor government led by Blair won its third and final term. By 2010, when Cameron ousted Gordon Brown, who had succeeded Blair as prime minister, the two parties shared a postwar low of 65.1 percent of the total ballots cast. About two-thirds of the remaining votes went to the Liberal Democrats, the centrist party that joined the Conservatives to form a governing coalition, with the rest diffusing among smaller alternatives, including nationalist parties in Scotland and Wales.

The same broad disillusionment with political leadership visible in the United States since the 1960s partly explains the decline of the major British parties. But most analysts here place more weight on the fraying links between class, culture, and political allegiance. Class distinctions have often appeared more overt and immovable in Britain than in the United States, and the U.K.'s two major parties reflected that, with Labor organically rooted in the working class, and the Tories relying on votes from the middle class and above.

Tim Bale, the author of The Conservative Party From Thatcher to Cameron and a professor of politics at Queen Mary University of London, is one of many British analysts who describe the parties' political support through most of the 20th century as "tribal" in its predictability and durability. "You were either one or the other, with class dominating political preferences," he said. But those preferences are much less reliable today. "Voters are so much more volatile, and they are increasingly not tied to either of the two major parties," Bale says.

Class allegiance still shapes political loyalty more in the United Kingdom than it does in the United States, but the British system has seen the same "class inversion" that has reshaped American politics. Like the American Democratic Party, the Labor Party saw its support grow (particularly under Blair) among middle-class professionals who tend toward liberal positions on social, environmental, and foreign policy issues; meanwhile, again like U.S. Democrats, Labor has lost support among working-class whites drawn to conservative arguments against taxes, welfare, and immigration. The Conservatives still rely to a greater degree on voters with more education than on those with less, but polls by the independent research firm YouGov suggest that Labor now draws its support about evenly from across the educational spectrum — a distribution that would have been unimaginable only a few decades ago. "There is still a positive correlation between class and [party preferences]," says Peter Kellner, president of YouGov, "but it is much weaker than it used to be." Instead, the most important fissure in British politics now is regional, with Labor controlling northern England, Scotland, and Wales, and the Tories strongest in southern England (except for Labor-favoring parts of London).

The erosion of tribal allegiances to the major parties provided more room for the Liberal Democrats to emerge as a full-scale third party after the 1980s, albeit one with a clear ceiling. In elections since the Thatcher era, the Liberal Democrats have usually captured between one-fifth and one-fourth of the total vote, often getting support from better-educated urban voters drawn to the party's general mix of environmentalism, internationalism, and fiscal restraint. (The party's leader, Nick Clegg, who serves as deputy prime minister to Cameron, represents an affluent university community.) However, the British "first-past-the-post" system rewards each legislative seat to the candidate who wins the most votes, without requiring a runoff if no one obtains a majority. As a result, the Liberal Democrats' share of seats in Parliament never approached its overall share of the vote. (The party often comes in second in both Labor strongholds and Conservative ones.) But by better targeting their efforts, the Liberal Democrats have significantly expanded their influence: They won almost exactly the same 23 percent of the vote in the 1987 and 2010 elections, but captured just 22 seats in the former and 57 in the latter.

As Kellner notes, the implications of the Liberal Democrats and smaller parties winning a greater number of seats in the Commons were for many years disguised, because the Conservatives behind Thatcher in the 1980s, and Labor behind Blair from 1997 through the first part of this century, dominated politics anyway. But with neither party enjoying such preponderant support in 2010, the Conservatives won only a plurality of 306 seats, falling well short of the 326 needed for a majority. That forced Cameron to forge his coalition deal with Clegg.

A NEW MODEL?

For the British political establishment, one of the most critical questions is whether the current coalition is an anomaly or a model that may become increasingly common in the decades ahead. Before 2010, no election had failed to produce a majority — thereby creating what the British call a "hung Parliament" — since the 1970s. (And even then the Labor Party tried to govern through an unstable "minority government" rather than negotiate a formal coalition.) The dominant view among the political leadership in the major parties probably tilts toward the expectation that coalitions will remain rare. "The party people will say this is an aberration," Riddell says. Prime ministers as different as Thatcher and Blair enjoyed almost untrammeled freedom. (CARL DE SOUZA/AFP/Getty Images)

But he is one of many observers who believe that expectation may be off the mark. Kellner, whose firm conducts exhaustive surveys on British opinion, likewise considers it more likely than not that the next election, scheduled for May 2015, will produce another hung Parliament. His firm's recent polls have found Labor attracting just under 40 percent of the vote and the Conservatives drawing about one-third. That's more than their combined share in 2010, but still not enough to guarantee a majority for either side. In addition, Kellner says, the historic pattern in which the governing party usually gains support in the final year before the election could move the two major contenders toward something even closer to a tie in the overall vote. Labor must also carry the weight of low ratings for its leader, Ed Miliband. (Miliband was introduced to the public in a Shakespearean swirl of drama: After Labor's 2010 defeat, he was selected as party leader when he unexpectedly challenged, and beat, his more centrist older brother, David Miliband, the outgoing foreign minister who had been the front-runner for the job.) Adding it up, Kellner concludes: "Unless something extraordinary happens, it is very likely we have another hung Parliament. It may be that we are entering a period of some decades where the new normality is a hung Parliament, which has not been the case for the past 80 years."

Tim Farron, a leading Liberal Democrat MP, echoes Kellner's prediction. "When you've got a multiparty democracy, you need one of the two main parties to have a really compelling narrative in order to get a majority — either hope or fear — and now there isn't such a thing," says Farron. "And so that leaves a situation where if there isn't a compelling reason for one to switch to the other "¦ I think there is probably a 60 percent chance of another hung Parliament."

Political analysts and operatives agree that a second consecutive hung Parliament would be a watershed in British politics. In most European nations, notes Riddell, the leading parties assume they will need to compromise and partner with at least one of the rivals they run against. That assumption hasn't yet seeped into the British system, which is still defined by open conflict (symbolized by the raucous weekly jousting of Prime Minister's Question Time). Yet if the 2015 result produces another coalition, Riddell predicts, the two major parties increasingly will be compelled to build "an anticipation of compromise" into their agendas. "If you expect coalition every time, your culture is different," he says.

Already, the operation of this coalition has previewed the changed dynamics by introducing more complexity and negotiation to a system that previously moved a single party's agenda into law with almost mechanized efficiency. On the biggest economic questions, all observers agree, the Conservatives and Liberal Democrats have locked arms to a surprising extent. Brushing past unwavering opposition from Labor, they have unified behind the core agenda of fiscal austerity shaped by George Osborne, the Conservative chancellor of the Exchequer, the government's chief economic official. Brady, the Conservative MP, is critical of the coalition on other fronts, but on the central tax and spending issues, he says the alliance with Liberal Democrats has been "very solid." Indeed, he says, public support for the agenda has probably increased because it's not just Conservatives touting it. "I think that [fiscal austerity] has been elevated by the coalition," he says. "It has given a remarkable solidity to that position." The result is that, on spending restraint, the coalition has produced "a Thatcherite government" with a record indistinguishable from the one a Conservative-only majority might have amassed, says Bale, the political scientist who studies the party.

The necessities of the coalition have complicated an already fraught relationship between Cameron and the Conservatives' far-right flank, which is growing in influence, as the tea party has in the United States.

But, in other ways, the Liberal Democrats have forced the Conservatives in directions they probably would not have gone alone. Liberal Democrats pressured the coalition's senior partners to exempt more low-income families from income taxes and to scale back a tax cut for the highest earners. Clegg, in his speech to the Liberal Democrat Party convention last September, listed almost a dozen other specific Conservative priorities, including inheritance-tax cuts, education reform, and restrictions on workplace rights, that he said his party had led its partner to shelve. On the environment, he insisted, the Liberal Democrats had fought the Conservative majority "tooth and nail" to "keep this government green." Cameron offered a backhanded acknowledgement of his allies' restraining influence when he recently told a conservative magazine he keeps a "little black book" of policies he would implement if the next election provided him a Conservative-only majority. "I feel very passionately that I want single-party government," he told The Spectator in December. These coalition cracks widened this month when Osborne signaled the government's intention to pursue further large reductions in welfare spending after the next election, and Clegg immediately denounced the proposal as "a monumental mistake."

Cameron and Clegg may be at least partly choreographing these complaints, as Labor Party strategists suspect, to motivate each party's partisans before the approaching election. But there's no question the coalition has jostled the conventional dynamics of British politics in ways large and small.

One of those ways has been to complicate the opposition for Labor, which has worked tirelessly to portray Cameron as favoring the wealthy. But one top Labor strategist acknowledges that some of the concessions the Liberal Democrats forced on the Tories (such as exempting more lower-income families from income taxes) have blurred that portrait. "There is a confusion in our attacks that comes from the fact that they have to keep a wide spectrum happy," the strategist said.

For the Liberal Democrats themselves, the coalition has been an emphatically mixed blessing. It has provided their greatest sustained influence on policy, but their public support in the polls has tumbled to about half its 2010 level, as left-of-center supporters disillusioned by the party's cooperation with Cameron have abandoned them for Labor. "In terms of our ability to make a difference, it's great," Farron says. "In terms of the electoral impact on the party, it's been very harsh indeed." Almost all observers expect the Liberal Democrats to lose seats in the next election, although the strong local ties many MPs have built should mean their numbers in Parliament won't fall as far as their decline in the overall vote share would suggest.

The necessities of the coalition have also further complicated an already fraught relationship between Cameron and the Conservatives' far-right flank, which is growing in influence, as the tea party has in the United States. While the Tories' right wing is comfortable with Cameron's economic agenda, it has always resisted other elements of his efforts to "modernize" the party — particularly his support for gay marriage and for environmental measures such as action against climate change. And the Right has always viewed Cameron as too cautious in resisting immigration and opposing Britain's participation in the European Union, which raises the same concerns about "sovereignty" among conservatives here that United Nations treaties do in the United States.

On these social, environmental, and international issues, many hard-right Tories grumble that the need to mollify Liberal Democrats has pulled the government away from their own party's core convictions. In particular, the February 2013 vote legalizing gay marriage — which passed only with broad support from Labor and Liberal Democrats after a majority of Tories rebelled — has rankled grassroots activists. "While quite a lot of the agenda of the government has been conservative, there is, nonetheless, a continuing — probably growing — sense among the traditional Conservative voters that the Conservative government doesn't share their interests," says Brady, who chairs the "1922 Committee," an influential organization of Tory conservatives.

Cameron has responded to that anxiety over the past year by shifting to the right on relations with Europe (he's promised, if reelected, to hold a referendum on whether the U.K. should leave the Union) and immigration (proposing to restrain benefits for migrants, and perhaps limit their entry overall, which would sharply depart from E.U. rules). He has also entrusted the Conservative reelection campaign to Lynton Crosby, a hard-edged, base-oriented Australian strategist, who is expected to sharpen the party attacks on welfare, immigration, and Europe — all of which will inevitably increase tensions with the Liberal Democrats.

But even so, Cameron's centrist impulses on some fronts, reinforced by the demands of coalition, have widened the opening for the two-decade-old UK Independence Party to potentially emerge as a fourth viable national party, although it controls no seats in the Commons today.

UKIP, as it is known, blends cultural conservatism, suspicion of immigrants and international institutions, and attacks on both welfare recipients and wealthy "elitists" — almost precisely the mix of policies championed in the United States by Pat Buchanan during the 1990s (and by other nativist European parties, such as France's National Front, today). Nigel Farage, UKIP's smooth, media-savvy leader, has shown a knack for connecting with lower-middle-class voters who feel left behind by the economy and both major parties. (YouGov's polls show that UKIP runs much better with blue-collar than white-collar workers.) Although the party criticizes both sides, it takes special glee in denouncing Cameron's conservatives as ideological quislings: "Diet Coke compared to the full flavor of us," says Tim Aker, who heads UKIP's policy unit. With surveys showing the party's national support spiking to double digits (after it attracted only about 3 percent of the vote in 2010), Aker says ebulliently, "2015 is a breakthrough election for us"¦. You've got four-party politics now."

OUTFLANKED

That's a bit premature. Because of the first-past-the-post electoral system, even if UKIP maintains its expanded support through the election — an uncertain proposition — it wouldn't gain many, if any, seats in Parliament; even Aker predicts only one to five. But Tories justifiably fear that by siphoning off enough right-leaning voters, UKIP could tip many other seats from Conservative to Labor.

With more combatants and multiple battlefronts, the British system is becoming less Guns of August and more Game of Thrones.

Among Conservative MPs, the fear of being outflanked on the right is reinforcing another striking trend in British politics: the breakdown of lockstep party unity in legislative votes. Philip Cowley and Mark Stuart, University of Nottingham professors who study voting trends, reported recently that with at least some members of the governing coalition dissenting on nearly 40 percent of its votes, Parliament since 2010 "remains on course to be the most rebellious since 1945." The particular complications of coalition may be inflating those numbers, but the trend toward fraying loyalty is larger. The post-World War II record for rebellions that this Parliament is likely to shatter is held by the Labor government that the coalition ousted. "Party discipline is a shadow of its former self," says Anthony King, the longtime student of British politics and a coauthor of the new book The Blunders of Our Governments.

The root of this change, many British observers believe, may be the same ebbing of tribal loyalty that is eroding the two parties' share of the overall vote. As attachments to the parties weaken, MPs feel more pressure to appeal to voters as individuals, which encourages them to display more individuality in their voting records. Once suspect, independence is now often an electoral asset. When Brady, for instance, resigned a few years ago from a party leadership post in protest of a Conservative education-policy shift that was unpopular with his constituency, it "was fully six months before I left my home without a stranger coming up to me and shaking my hand," he says. "By being more independent, more the local champion, I think more of us can build a level of support in our local constituencies separate from party."

The existence of the coalition has actually facilitated these rebellions, by making it easier for the Conservative right flank (the most frequent dissenters) to oppose Cameron without actually defeating him, because the Liberal Democrats can usually compensate for their lost votes. But the turmoil has produced some losses for Cameron — on political reform, European Union funding, and the Syria authorization — and few here would be surprised if legislative defeats for the governing party become more common.

The erosion of party discipline reinforces the other big changes in British politics: the declining share of the major-party vote, the emergence of a third (and potentially, with UKIP, even a fourth) viable national party, and the growing likelihood of future governing coalitions. All are steadily transforming a political system built on binary trench warfare into a jumbled competition with more combatants and multiple battlefronts: less Guns of August and more Game of Thrones.

This new environment means that British policy increasingly will require negotiation, accommodation, and what Riddell, the Institute for Government director, calls "perpetual compromise" among a wider range of factions and interests than in previous generations. That shift will provide a vivid counterpoint — and likely some important lessons — as the American political system, spurred by unrelenting polarization, burrows more deeply into the trenches.

A NEW MODEL?

For the British political establishment, one of the most critical questions is whether the current coalition is an anomaly or a model that may become increasingly common in the decades ahead. Before 2010, no election had failed to produce a majority — thereby creating what the British call a "hung Parliament" — since the 1970s. (And even then the Labor Party tried to govern through an unstable "minority government" rather than negotiate a formal coalition.) The dominant view among the political leadership in the major parties probably tilts toward the expectation that coalitions will remain rare. "The party people will say this is an aberration," Riddell says. Prime ministers as different as Thatcher and Blair enjoyed almost untrammeled freedom. (CARL DE SOUZA/AFP/Getty Images)

But he is one of many observers who believe that expectation may be off the mark. Kellner, whose firm conducts exhaustive surveys on British opinion, likewise considers it more likely than not that the next election, scheduled for May 2015, will produce another hung Parliament. His firm's recent polls have found Labor attracting just under 40 percent of the vote and the Conservatives drawing about one-third. That's more than their combined share in 2010, but still not enough to guarantee a majority for either side. In addition, Kellner says, the historic pattern in which the governing party usually gains support in the final year before the election could move the two major contenders toward something even closer to a tie in the overall vote. Labor must also carry the weight of low ratings for its leader, Ed Miliband. (Miliband was introduced to the public in a Shakespearean swirl of drama: After Labor's 2010 defeat, he was selected as party leader when he unexpectedly challenged, and beat, his more centrist older brother, David Miliband, the outgoing foreign minister who had been the front-runner for the job.) Adding it up, Kellner concludes: "Unless something extraordinary happens, it is very likely we have another hung Parliament. It may be that we are entering a period of some decades where the new normality is a hung Parliament, which has not been the case for the past 80 years."

Tim Farron, a leading Liberal Democrat MP, echoes Kellner's prediction. "When you've got a multiparty democracy, you need one of the two main parties to have a really compelling narrative in order to get a majority — either hope or fear — and now there isn't such a thing," says Farron. "And so that leaves a situation where if there isn't a compelling reason for one to switch to the other "¦ I think there is probably a 60 percent chance of another hung Parliament."

Political analysts and operatives agree that a second consecutive hung Parliament would be a watershed in British politics. In most European nations, notes Riddell, the leading parties assume they will need to compromise and partner with at least one of the rivals they run against. That assumption hasn't yet seeped into the British system, which is still defined by open conflict (symbolized by the raucous weekly jousting of Prime Minister's Question Time). Yet if the 2015 result produces another coalition, Riddell predicts, the two major parties increasingly will be compelled to build "an anticipation of compromise" into their agendas. "If you expect coalition every time, your culture is different," he says.

Already, the operation of this coalition has previewed the changed dynamics by introducing more complexity and negotiation to a system that previously moved a single party's agenda into law with almost mechanized efficiency. On the biggest economic questions, all observers agree, the Conservatives and Liberal Democrats have locked arms to a surprising extent. Brushing past unwavering opposition from Labor, they have unified behind the core agenda of fiscal austerity shaped by George Osborne, the Conservative chancellor of the Exchequer, the government's chief economic official. Brady, the Conservative MP, is critical of the coalition on other fronts, but on the central tax and spending issues, he says the alliance with Liberal Democrats has been "very solid." Indeed, he says, public support for the agenda has probably increased because it's not just Conservatives touting it. "I think that [fiscal austerity] has been elevated by the coalition," he says. "It has given a remarkable solidity to that position." The result is that, on spending restraint, the coalition has produced "a Thatcherite government" with a record indistinguishable from the one a Conservative-only majority might have amassed, says Bale, the political scientist who studies the party.

The necessities of the coalition have complicated an already fraught relationship between Cameron and the Conservatives' far-right flank, which is growing in influence, as the tea party has in the United States.

But, in other ways, the Liberal Democrats have forced the Conservatives in directions they probably would not have gone alone. Liberal Democrats pressured the coalition's senior partners to exempt more low-income families from income taxes and to scale back a tax cut for the highest earners. Clegg, in his speech to the Liberal Democrat Party convention last September, listed almost a dozen other specific Conservative priorities, including inheritance-tax cuts, education reform, and restrictions on workplace rights, that he said his party had led its partner to shelve. On the environment, he insisted, the Liberal Democrats had fought the Conservative majority "tooth and nail" to "keep this government green." Cameron offered a backhanded acknowledgement of his allies' restraining influence when he recently told a conservative magazine he keeps a "little black book" of policies he would implement if the next election provided him a Conservative-only majority. "I feel very passionately that I want single-party government," he told The Spectator in December. These coalition cracks widened this month when Osborne signaled the government's intention to pursue further large reductions in welfare spending after the next election, and Clegg immediately denounced the proposal as "a monumental mistake."

Cameron and Clegg may be at least partly choreographing these complaints, as Labor Party strategists suspect, to motivate each party's partisans before the approaching election. But there's no question the coalition has jostled the conventional dynamics of British politics in ways large and small.

One of those ways has been to complicate the opposition for Labor, which has worked tirelessly to portray Cameron as favoring the wealthy. But one top Labor strategist acknowledges that some of the concessions the Liberal Democrats forced on the Tories (such as exempting more lower-income families from income taxes) have blurred that portrait. "There is a confusion in our attacks that comes from the fact that they have to keep a wide spectrum happy," the strategist said.

For the Liberal Democrats themselves, the coalition has been an emphatically mixed blessing. It has provided their greatest sustained influence on policy, but their public support in the polls has tumbled to about half its 2010 level, as left-of-center supporters disillusioned by the party's cooperation with Cameron have abandoned them for Labor. "In terms of our ability to make a difference, it's great," Farron says. "In terms of the electoral impact on the party, it's been very harsh indeed." Almost all observers expect the Liberal Democrats to lose seats in the next election, although the strong local ties many MPs have built should mean their numbers in Parliament won't fall as far as their decline in the overall vote share would suggest.

The necessities of the coalition have also further complicated an already fraught relationship between Cameron and the Conservatives' far-right flank, which is growing in influence, as the tea party has in the United States. While the Tories' right wing is comfortable with Cameron's economic agenda, it has always resisted other elements of his efforts to "modernize" the party — particularly his support for gay marriage and for environmental measures such as action against climate change. And the Right has always viewed Cameron as too cautious in resisting immigration and opposing Britain's participation in the European Union, which raises the same concerns about "sovereignty" among conservatives here that United Nations treaties do in the United States.

On these social, environmental, and international issues, many hard-right Tories grumble that the need to mollify Liberal Democrats has pulled the government away from their own party's core convictions. In particular, the February 2013 vote legalizing gay marriage — which passed only with broad support from Labor and Liberal Democrats after a majority of Tories rebelled — has rankled grassroots activists. "While quite a lot of the agenda of the government has been conservative, there is, nonetheless, a continuing — probably growing — sense among the traditional Conservative voters that the Conservative government doesn't share their interests," says Brady, who chairs the "1922 Committee," an influential organization of Tory conservatives.

Cameron has responded to that anxiety over the past year by shifting to the right on relations with Europe (he's promised, if reelected, to hold a referendum on whether the U.K. should leave the Union) and immigration (proposing to restrain benefits for migrants, and perhaps limit their entry overall, which would sharply depart from E.U. rules). He has also entrusted the Conservative reelection campaign to Lynton Crosby, a hard-edged, base-oriented Australian strategist, who is expected to sharpen the party attacks on welfare, immigration, and Europe — all of which will inevitably increase tensions with the Liberal Democrats.

But even so, Cameron's centrist impulses on some fronts, reinforced by the demands of coalition, have widened the opening for the two-decade-old UK Independence Party to potentially emerge as a fourth viable national party, although it controls no seats in the Commons today.

UKIP, as it is known, blends cultural conservatism, suspicion of immigrants and international institutions, and attacks on both welfare recipients and wealthy "elitists" — almost precisely the mix of policies championed in the United States by Pat Buchanan during the 1990s (and by other nativist European parties, such as France's National Front, today). Nigel Farage, UKIP's smooth, media-savvy leader, has shown a knack for connecting with lower-middle-class voters who feel left behind by the economy and both major parties. (YouGov's polls show that UKIP runs much better with blue-collar than white-collar workers.) Although the party criticizes both sides, it takes special glee in denouncing Cameron's conservatives as ideological quislings: "Diet Coke compared to the full flavor of us," says Tim Aker, who heads UKIP's policy unit. With surveys showing the party's national support spiking to double digits (after it attracted only about 3 percent of the vote in 2010), Aker says ebulliently, "2015 is a breakthrough election for us"¦. You've got four-party politics now."

OUTFLANKED

That's a bit premature. Because of the first-past-the-post electoral system, even if UKIP maintains its expanded support through the election — an uncertain proposition — it wouldn't gain many, if any, seats in Parliament; even Aker predicts only one to five. But Tories justifiably fear that by siphoning off enough right-leaning voters, UKIP could tip many other seats from Conservative to Labor.

With more combatants and multiple battlefronts, the British system is becoming less Guns of August and more Game of Thrones.

Among Conservative MPs, the fear of being outflanked on the right is reinforcing another striking trend in British politics: the breakdown of lockstep party unity in legislative votes. Philip Cowley and Mark Stuart, University of Nottingham professors who study voting trends, reported recently that with at least some members of the governing coalition dissenting on nearly 40 percent of its votes, Parliament since 2010 "remains on course to be the most rebellious since 1945." The particular complications of coalition may be inflating those numbers, but the trend toward fraying loyalty is larger. The post-World War II record for rebellions that this Parliament is likely to shatter is held by the Labor government that the coalition ousted. "Party discipline is a shadow of its former self," says Anthony King, the longtime student of British politics and a coauthor of the new book The Blunders of Our Governments.

The root of this change, many British observers believe, may be the same ebbing of tribal loyalty that is eroding the two parties' share of the overall vote. As attachments to the parties weaken, MPs feel more pressure to appeal to voters as individuals, which encourages them to display more individuality in their voting records. Once suspect, independence is now often an electoral asset. When Brady, for instance, resigned a few years ago from a party leadership post in protest of a Conservative education-policy shift that was unpopular with his constituency, it "was fully six months before I left my home without a stranger coming up to me and shaking my hand," he says. "By being more independent, more the local champion, I think more of us can build a level of support in our local constituencies separate from party."

The existence of the coalition has actually facilitated these rebellions, by making it easier for the Conservative right flank (the most frequent dissenters) to oppose Cameron without actually defeating him, because the Liberal Democrats can usually compensate for their lost votes. But the turmoil has produced some losses for Cameron — on political reform, European Union funding, and the Syria authorization — and few here would be surprised if legislative defeats for the governing party become more common.

The erosion of party discipline reinforces the other big changes in British politics: the declining share of the major-party vote, the emergence of a third (and potentially, with UKIP, even a fourth) viable national party, and the growing likelihood of future governing coalitions. All are steadily transforming a political system built on binary trench warfare into a jumbled competition with more combatants and multiple battlefronts: less Guns of August and more Game of Thrones.

This new environment means that British policy increasingly will require negotiation, accommodation, and what Riddell, the Institute for Government director, calls "perpetual compromise" among a wider range of factions and interests than in previous generations. That shift will provide a vivid counterpoint — and likely some important lessons — as the American political system, spurred by unrelenting polarization, burrows more deeply into the trenches.