Lucas Jackson / Reuters

Last night’s Democratic debate showed how America’s political parties have turned upside down. At center stage stood Bernie Sanders and Elizabeth Warren, making arguments about decriminalizing illegal border crossings and abolishing private health insurance that would have sounded fantastical just a few years ago. Throwing darts from the edges were John Delaney, Steve Bullock, John Hickenlooper, and Tim Ryan—candidates garnering less than 1 percent in national polls—whose relatively centrist views sounded like Barack Obama’s.

It was an inversion of the way debates have generally played out in the past. Since at least the 1980s, presidential primary campaigns have generally featured front-runners, drawn from the party establishment, who defend a fairly centrist agenda against insurgents from the ideological extremes. In 1984 and 1988, the Democratic insurgent was Jesse Jackson, who took on insider favorites Walter Mondale and Michael Dukakis. In 2004, it was Howard Dean, against John Kerry. In 2016, it was Bernie Sanders, against Hillary Clinton. In the Republican Party, Pat Robertson challenged George H. W. Bush in 1988, Pat Buchanan challenged Bob Dole in 1996, and Ron Paul challenged Mitt Romney in 2012.

In the GOP, the standard script flipped in 2016. In the primary debates, Donald Trump, sometimes accompanied by another outlandish amateur, Ben Carson, occupied center stage, while establishment moderates including Jeb Bush and John Kasich challenged them from the sidelines. Last night in Detroit, Democrats witnessed the same pattern. Sanders and Warren, the ideological hard-liners, so dominated the discussion that the leading moderates—Pete Buttigieg, Beto O’Rourke, and Amy Klobuchar—faded into the background, leaving marginal candidates like Delaney to defend centrist positions held by the latest Democratic president less than four years ago.

How did the outsiders become insiders and the insiders outsiders? One answer is the financial crisis, and escalating inequality that has followed in its wake. Before it, Democrats were far more comfortable with America’s economic system than they are now. In 2000, former Goldman Sachs Chairman and Treasury Secretary Robert Rubin was so popular in Democratic circles that newspapers speculated Al Gore might make him his running mate. Obama chose as three of his first four chiefs of staff men who had worked in investment banks or hedge funds, with little Democratic outcry. Search transcripts of the 2008 Democratic primary debates and you’ll find variants of corporation mentioned only two, four, five, or seven times.

Last night in Detroit, the candidates called out corporations 21 times. Warren and Sanders repeatedly invoked their treachery to rhetorically dominate the candidates’ more moderate foes. During the debate, Delaney and Hickenlooper again and again touted their business experience and argued that Sanders’s and Warren’s plans were impractical. But again and again, their critiques were overshadowed when Warren denounced “the giant corporations that have taken our government and that are holding it by the throat” and when Sanders demanded a “political revolution that tells these billionaires and corporate America that they are Americans; they’ll participate in our society, but they have got to start paying their fair share of taxes, period”—after which the audience erupted in applause.

A second shift that has helped turn the Democratic Party inside out is the internet, which allows candidates to demonize business interests and the rich—the traditional source of campaign funds—yet still raise vast sums. The clearest historical precursor for Sanders and Warren’s campaigns is Jesse Jackson, whose 1984 convention speech attacked “those 90,000 corporations that made a profit last year but paid no federal taxes.” But Jackson raised less than a third of the money Mondale did. He was even out-fundraised by John Glenn, a centrist dud who withdrew from the race in mid-March.

This year, by contrast, Warren has raised almost as much money as Joe Biden while forswearing fundraisers with big donors. In the second quarter of this year, her average donor gave $28. For Sanders, it was $20.

The third factor that has capsized the traditional relationship between Democratic moderates and insurgents is the radicalization of the GOP. Barack Obama spent much of his presidency predicting that the Republicans’ ideological “fever” would break and the two parties would ultimately work together on health care, immigration, climate change, and gun control. Had that happened, Sanders and Warren might not be at center stage, and John Hickenlooper and Steve Bullock might not be mired below 1 percent in the polls.

The Affordable Care Act—which bore a distinct resemblance to the health-care plan Mitt Romney had pushed as governor of Massachusetts—gave private health insurers incentives to expand coverage and reduce costs. Had congressional Republicans helped it succeed rather than tried relentlessly to undermine it, Sanders and Warren would have a harder time arguing for abolishing private insurance today. Had the GOP agreed to Obama’s call for a cap-and-trade system to limit carbon emissions a decade ago, Democrats might not now be rallying around the Green New Deal. Republican’s success in frustrating modest reforms has liberated Democrats to propose more radical change.

The radicalization of the GOP has also undermined Democrats who call for transcending America’s divisions or urge compromise by both sides. In his keynote address at the 2004 Democratic convention, Obama said, “There’s not a black America and white America and Latino America and Asian America; there’s the United States of America.” For a Democrat to utter such post-racial language during Donald Trump’s presidency would sound absurd. In The Audacity of Hope, Obama chided “liberals” who get “riled up about government encroachments on … a woman’s reproductive freedoms” but react with a “blank stare” when told “about the potential costs of regulation to a small-business owner.” Democrats are less open to such analogies when states are passing laws all but outlawing abortion.

There were candidates on stage last night who, like Obama, pledged to overcome America’s ideological divide. Hickenlooper, a former Colorado governor, boasted that, in his state, “we got people together” across party lines “to get things done.” Representative Tim Ryan said his agenda was “not left or right” but “new and better.” But those “Kumbaya” arguments don’t work as well when 86 percent of Democrats think the Republican president—who enjoys overwhelming Republican support—is a racist.

In tonight’s debate, of course, the setup will look different. Joe Biden, an establishment moderate who leads the polls, will hold center stage. He is the last remnant of a political order that dominated both parties for generations. If he can’t defend his perch more effectively than he did in June, that old order may crumble once and for all.

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