Larry Downing/Reuters

As polls show a movement toward Republicans—the new ABC News/Washington Post survey shows a 6-point GOP advantage in the generic ballot—there is increasing interest in what would happen over the next two years with Republican control of both the House and Senate. I first addressed the prospect of a Republican Senate in March, and I wrote last week about how independents could shake up the balance in an evenly divided Senate. Now, some more reflections on governance with a Republican Congress in the final two years of a two-term Democratic president.

I confess I laughed out loud at George Will's gushing encomium to Mitch McConnell, predicting that McConnell, who "burns in indignation" at the degradation of his beloved Senate, "would … emulate his model of majority leadership—the 16 years under a Democrat, Montana's Mike Mansfield. He, like McConnell, had a low emotional metabolism but a subtle sense of the Senate's singular role in the nation's constitutional equilibrium." I knew Mansfield, who was taciturn but had immense dignity and, when you got to know him, warmth. He put process ahead of politics and decency ahead of ambition. To be frank, I don't see a lot of Mansfield in McConnell (as I noted last week, the best portrait of McConnell comes in a new ebook by Alec MacGillis called The Cynic. The best portrait of Mansfield is in a book by journalist Don Oberdorfer, titled Senator Mansfield: The Extraordinary Life of a Great American Statesman and Diplomat. Not many parallels there.)

I do see in McConnell a workhorse, an extraordinarily bright man and master politician who knows the Senate and its rules thoroughly, and who has managed quite remarkably to keep his Republican colleagues in the Senate united. And I will give him the benefit of the doubt, that he wants to return the Senate to the regular order, with longer work weeks, open amendments, and real debates. But we also know what McConnell himself has said to the major-league GOP donors whose opinions matter more than anyone else: that he will work at every turn to thwart the Obama agenda, and use appropriations and the budget process to force the president to roll back key elements of Obamacare, to water down Dodd-Frank, to tilt toward coal (and more oil drilling and natural-gas fracking), to move forward on the Keystone XL pipeline, and to stop Environmental Protection Agency action on climate change.

With the exception of a reconciliation package that can be done with 51 votes in the Senate, everything else will take 60 votes to overcome filibusters (I am assuming that McConnell, burning with indignation at the Harry Reid-led Senate, will not degrade it further by his own filibuster nuclear option). Perhaps there will be a few cases—say, a single-shot repeal of the medical-device tax, a bill to force approval of Keystone—where he can find a bipartisan majority and maybe avoid a filibuster, only to end up with a veto.

Budget reconciliation—used by George W. Bush and congressional Republicans for his tax cuts, among other controversial policies, and by President Obama and Democrats for the Affordable Care Act—is a potentially powerful weapon that can encompass substantive policy changes under a budget rubric. But even getting 51 votes for something that will satisfy a majority of House Republicans, which will itself be quite hard-edged and radical, will not be easy. It will take winning over Susan Collins and a slew of Republican senators up in 2016, including many in blue states. Among them: Kelly Ayotte, Pat Toomey, Dan Coats, Lisa Murkowski, Roy Blunt, and Mark Kirk.

Perhaps McConnell can prevail—after all, he managed to get Olympia Snowe and John McCain, the key players in campaign finance reform, to vote to kill the Disclose Act in the aftermath of Citizens United. But Obama would surely veto a bill that eviscerated his main presidential accomplishments, and a showdown would result in a government shutdown. That is not exactly a winning strategy for Mitch.

What about avoiding Democratic filibusters on bills by opening up the process to amendments? Here, brutal reality will intrude. A Republican Senate will have either 51, 52, or—if it really breaks the GOP way—53 Republicans. But three to five of those—Rand Paul, Ted Cruz, Marco Rubio, and perhaps John Thune and Rob Portman—will be running for president. That means they will be AWOL more often than not from the Senate, leaving McConnell more often than not with fewer Republicans than Democrats in the Senate. And that means jeopardy for votes on amendments.

But even if McConnell could muster all his troops, imagine Democrats salivating at the prospect of offering a series of "gotcha" amendments to bills, like one approving the Keystone pipeline, designed to target and embarrass the Republicans up for reelection in tough states like New Hampshire and Pennsylvania. Would McConnell be less likely than his counterpart Harry Reid to try to insulate his vulnerable colleagues from those difficult votes? I doubt it.

Of course, a Majority Leader McConnell would have other weapons at his disposal to pressure or thwart the president. He would use the confirmation process to block executive appointees (forget about most judicial slots being filled) or try to pressure Obama to make policy concessions in order to get his important nominees confirmed. He and his colleagues will ramp up investigations; tie up key Obama Cabinet and agency officials by requiring them to testify in front of multiple committees; and issue flurries of subpoenas to the White House to paralyze the White House Counsel's office, in turn making it harder for the president to draft and use executive orders. Who will be the Senate's Darrell Issa? Maybe Chuck Grassley, who has become more and more shrill over the past six years.

We can't forget the House, which has been largely lost in the dialogue. A few weeks back, Speaker John Boehner talked about his headaches, including having about 16 "knuckleheads" in his own caucus. There will be more Republicans in the next House—but more knuckleheads, too, maybe doubling the number. Boehner and the leadership team can likely stay intact, but not without some heartburn and not without making some promises to potential apostates about doubling down on domestic spending cuts and measures to thwart or embarrass Obama.

While Majority Leader Kevin McCarthy has talked about pivoting to a new, positive agenda—including passing an extended budget and spending agreement via continuing resolution in the lame-duck session to take those contentious issues off the table—it is no easy thing to do. Will the CR simply ratify the status quo until October brings the next fiscal year? Will House Republicans accept that deal without demanding more spending for defense and more cuts in domestic spending? Perhaps, to avoid a meltdown before they take all the congressional reins of power. But what happens when the next year's appropriations bills, and the next year's budget, start moving early next year, bringing with them a return to the mindless and damaging across-the-board cuts that were postponed for two years in the Ryan-Murray spending deal?

McCarthy is talking regularly with Thune to avoid the usual tension and problems with the Senate. That is nice—but even if McCarthy and Thune see eye to eye, the culture of the Senate, the requirement of unanimous consent to begin action, the existence of the filibuster, and the different world views of many senators compared with their House counterparts makes coordination between the bodies so, so difficult. Remember that Speaker Newt Gingrich was far more unhappy with Senate Majority Leader Bob Dole than he was with President Clinton under similar circumstances in 1995-96.

The desire of McCarthy and other GOP leaders to avoid a characterization of their party as the party of no—of obstructionism but no ideas—by showing an ability to govern, will come into conflict with a GOP base that wants to continue the take-no-prisoners approach that worked so well in 2010, and again, if this scenario prevails, in 2014. And the presidential campaign will give added traction to the primary and caucus voters who are dominated by the hardest of hardliners, and the collection of presidential candidates who will pound away against the Common Core, immigration legislation, any taxes, or any spending except for defense and the border.

I do not think this means total gridlock. The ability to pass some things that are a bit below the radar, like trade and prison reform, is clear. There is a smaller chance of passing things like an infrastructure bank, or an increase in the Earned Income Tax Credit. There is a smaller chance yet of enacting some form of bipartisan tax reform. What about the kind of deal Rob Portman pitched to my colleague Molly Ball—acceptance of the Keystone pipeline in return for a bipartisan agreement on reductions in carbon emissions? Try to get that through the House!

Finally, I have to at least mention the "I" word. I have talked off the record to some aides to Tea Party Republicans in the House, who say that they are getting a lot of push from their activist voters to impeach the president. They, like their leaders, know how catastrophic that would be for Republicans heading into 2016 and will do what they can to head off any such move by hotheads. But if we assume that the president, determined to enhance and extend his legacy, implements major executive orders on immigration and climate change, there will be howls of outrage from the base and many lawmakers, and the likes of Rush Limbaugh, Sean Hannity, Mark Levin, Erick Erickson, and Laura Ingraham will not be holding them back. More than likely, neither would Ted Cruz. Another challenge for House and Senate Republican leaders to keep their party from veering off the edge.

Both parties have their challenges. But the most interesting ones to watch will be those between and among a Republican Senate, a Republican House, and a set of Republican presidential candidates pulling the party's center of gravity further to the right—meaning the tension between setting out and making concrete a positive agenda for governing and the pressure to continue to block and obstruct will be very, very high.

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