It has been a difficult year for Republicans in Congress, watching as their party nominated Donald Trump for president, not only squandering an opportunity to take control of all three branches of government, but forcing them to answer for every damn fool thing that comes out of Trump's mouth as they try to hold on to their own seats.

And as the Nov. 8 election approaches, things are only getting worse.

No one has made a greater public performance of his anguish than Speaker of the House Paul Ryan, who endorsed Trump but has taken every opportunity to express how disappointed he is in the nominee's latest outburst. On Monday, after a weekend that saw the release of a tape on which Trump brags that he can sexually assault women with impunity because he's famous, followed by a debate in which Trump offered women voters yet more reasons to reject him, Ryan told a conference call full of Republican members of Congress that he'd no longer be campaigning for Trump or defending him publicly.

Afterward, The New York Times reported, "a stream of hard-liners came on the line to urge their colleagues not to give up on Mr. Trump, and complained that Mr. Ryan was effectively conceding the presidency." Ryan then came back on the call to reassure them that he wasn't formally un-endorsing Trump, but would devote his efforts from here on out to maintaining the GOP majority in the House. Naturally, Trump took to Twitter to hit back, saying "Paul Ryan should spend more time on balancing the budget, jobs and illegal immigration and not waste his time on fighting Republican nominee."

A public mini-feud between a party's presidential nominee and its highest-ranking elected official (and be assured that Ryan knew full well what he said on that call would be related to the press) is just one of the unprecedented features of the GOP's awkward position. Even before the debate, the list of Republican officeholders formally rejecting Trump had grown into the dozens. There may never have been a major party nominee with so much opposition from his own party.

The proximate cause is that tape, and there are reasons why it has had such a profound political impact, the most important being that it's on video, in Trump's own voice. That creates a much more powerful impact than someone's testimony about what happened or even a transcript, which we find easier to dismiss or discount (and the video can be replayed on the news and online again and again). Try to imagine you're a congressman getting queries from reporters and constituents about it, having to figure out how to walk the line of condemning the remarks while supporting the man who made them.

The more Trump slides in the polls and the more he seems headed for defeat, the more Republicans will have an incentive to jump ship in an attempt to save their own skins. It starts with those in districts and states that lean Democratic or are closely divided; if he drops a few more points, members from districts that lean Republican but not too strongly will suddenly see the value in distancing themselves from him.

But either way they turn, there's danger. After Ryan disinvited Trump from what was supposed to be a unity rally over the weekend, he found himself heartily booed by angry Trump supporters. Other Republicans could face the same thing. While Trump pushes away wavering moderate Republicans, his strategy seems designed only to solidify his support among those who already love him, and they won't take kindly to quisling Republicans who turn on their nominee just because he does a little thing like admit to a pattern of sexual assault.

Ryan, like all the other Republicans contemplating their relationship to Trump, has a keen eye on his future. If he rejects Trump outright, he can say that he was a man of conscience who saw the damage being done to the party, but he'll also court a backlash from colleagues and voters who'll regard him as a traitor who helped Hillary Clinton get elected. But if he doesn't stand in Trump's way and the election turns out to be a complete disaster, he'll have to answer for why he didn't do more to stop Trump from doing so much damage to their party.

That dilemma is one of the things that will make Republican politics in 2017 and beyond so interesting. How will the party understand what it went through in 2016? If they learn the right lessons, can they put them into practice even if they want to? Or will they continue to find it necessary to pander to a base that's angry at their leaders, angry at a changing society, and angry when Trump doesn't win?

Trump himself will certainly stoke that anger. He's doing it already. "So many self-righteous hypocrites. Watch their poll numbers — and elections — go down!" he tweeted on Sunday as the cascade of Republican defections continued.

What will Trump do after the election if he loses? Apart from more angry tweets, it's hard to imagine him leading some kind of crusade to take vengeance upon the Republicans who betrayed him — simply because it would be too much work. The idea that Trump and his famously short attention span will want to invest time and effort into building some kind of outsider political movement with uncertain rewards stretches the imagination. It's much more likely that he'll bid politics goodbye and go back to licensing his (much diminished) brand.

But before we get to that point, Trump and Republicans in Congress could be posing a new danger to each other the worse their relationship gets. As my friend the political scientist Thomas Schaller observes, this infighting could produce a two-way roll-off effect that we haven't seen before. Roll-off is when some people vote for president, but don't bother voting for other offices; it happens to a degree in every election, usually because some voters just aren't interested in the other races or don't know who to vote for. But this year, the anger of Trump supporters "raises the prospect that some of these Trump voters will show up on election day, vote Trump, and spite some or all downballot Republican candidates by skipping these contests. This would magnify the normal roll-off effect," he says. At the same time, "a significant number of reliable Republican voters may skip the presidential [ballot] but vote for some or all of the remaining races." The result could be "lost votes for Trump at the presidential level and lost votes at the sub-presidential level for all other Republicans. That is the disaster scenario for the GOP."

Now maybe that won't happen. Maybe Republicans will stop defecting from Trump, and they'll all kiss and make up before election day. Or maybe there'll be yet another Trump scandal, causing even more Republicans to defect, Trump will get even angrier at them, and the feud will deepen. I know which one I think is more likely.