With one week to go, Donald Trump and Hillary Clinton are in a statistical dead heat nationally. The Fix's Chris Cillizza explains what you should expect from the last week of the election. (Peter Stevenson/The Washington Post)

It's a certified trend at this point: House and Senate Republicans who just a few weeks ago said they wanted Donald Trump to drop out of the presidential race are suddenly making it very clear that they're still voting for him anyway.

Or, in the case of House Speaker Paul D. Ryan (R-Wis.), they're making clear they already voted for Trump. Ryan broke up with the Republican nominee last month, yet he told Fox News Channel's Steve Doocy on Tuesday:

The result is a rather audacious attempt to Jedi mind-trick voters into believing these candidates really were for Trump the whole time. But why attempt such a blatantly political act so close to the election?

Two words: self preservation.

Actually, let's add two more related words: Trump supporters.

When at least four GOP senators left Trump after The Tape™, it looks like they underestimated both their nominee's resilience and his resonance with their base. A wave of daily Washington Post-ABC News tracking polls finds that Republican voters are coming home to Trump, too, and that the race is more or less tied (at least at the national level).

Meanwhile, unlike politicians, most Trump supporters never really left Trump after the 2005 tape at all. Which means the lawmakers who flipped on him realized that they had no (political) choice but to recalculate and flop back. "There is an intensity to the Trump voter that I haven’t seen in my life in politics,” longtime Republican pollster Frank Luntz told my Washington Post colleague Mike DeBonis recently.

But within the same category of concern, these Trump flip-floppers were each driven by slightly different factors. So let's break them down into three categories:

1. The red-staters

Sen. John Thune (R-S.D.). (Chip Somodevilla/Getty Images)

What they're worried about: Being primaried next time around.

Who's in this category: Sen. John Thune* (S.D.) (Senate Republicans' No. 3), Mike Crapo (Idaho) and Deb Fischer (Nebraska), among others.

What they've said: They've gone from something like this:

To this, via Crapo: "Though I thought and felt we needed a different choice, that’s not what we’re going to get, and we cannot elect Hillary Clinton for many reasons," he said recently. "... Given that choice, I will vote for the Republican ticket: Trump and Pence."

*UPDATE: Thune still thinks Pence should be the nominee. But given there are no other options, he's said he'll vote for Trump. Also, we should note that Thune is incredibly popular in South Dakota. In his 2010 election, he faced no Republican nor Democratic challenger and he won with literally 100 percent of the vote.

Their motivation to flip-flop: Thune and Crapo are up for reelection this year, but they're facing nominal challengers. These politicians are more likely thinking about future elections and whether NOT supporting Trump could lead to tougher fights next time around.

"Down-ballot GOPers are trying to figure out what's more likely in a future cycle: losing a primary to a Trump-lite or losing a general election to a Democrat," said Josh Chafetz, a Cornell law professor and congressional expert. "If they're more worried about the former, then they're more likely to back Trump in some way; if they're more worried about the latter, then they won't."

These red-staters are probably looking at data such as the Post-ABC tracking poll, which finds traditional Republican voters (white evangelical Protestants, conservatives, rural voters, white men) coalescing around Trump as the campaign enters its final week. And Trump supporters are actually more enthusiastic about their candidate than Clinton supporters are.

The wannabe future stars

House Oversight and Government Reform Committee Chairman Jason Chaffetz (R-Utah). (Brett Carlsen/Associated Press)

What they're worried about: Their résumés.

List includes: Rep. Jason Chaffetz (R-Utah) and Ryan.

What they've said: Stuff like this:

Their motivation to flip-flop: Let's start with Chaffetz. He is from a Republican state that isn't terribly fond of Trump. After the tape, he was one of the first to say he was "out."

But as the party coalesced around Trump, Chaffetz soon realized that being "out" when it comes to Trump could keep him "out" of his career. He's the chairman of the House Oversight and Government Reform Committee, he briefly ran for speaker last year and he's set up to be one of the main GOP antagonists to a President Hillary Clinton. If he wants his star to keep rising, he calculated he better at least vote for the party's nominee.

"His self-preservation here is likely more about avoiding claims that he abandoned the party from other elites than it is about voters," said Molly Reynolds, a congressional expert with the Brookings Institution.

Chaffetz's 180 in particular has come across as incredibly politically calculating. And, said Cornell Professor Chafetz: "It's hard to see what benefit he'll get out of it. Trump supporters will still be mad at him (just as they're mad at Ryan), and Democrats in a future general election will still be able to say that he supported Trump in the end. "

Meanwhile, Ryan appears to be in self-preservation mode. There have been signs that since he broke up with Trump in the days after The Tape, his support within the party is crumbling: Another Post-ABC News poll found that two-thirds of Republican-leaning likely voters disapprove of Ryan's decision not to campaign for Trump in the final few weeks. (Or, technically, ever, because the two have never appeared on a stage together.)

The competitive seat-ers

Rep. Joe Heck (R-Nev.) is running for the Senate. (Erik Verduzco/Las Vegas Review-Journal via Associated Press)

What they're worried about: Keeping their jobs

This group includes: Sen. Mark Kirk (Ill.), Rep. Joe Heck (Nev.) (currently running for his state's open Senate seat).

What they've said: No way are they voting for Trump. Here's Kirk, one of the most vulnerable GOP incumbents this cycle, in response to the tape:

But no way are these lawmakers voting for Clinton, either. Here's Heck, who's in a close race to replace outgoing Harry Reid in Nevada, to Talking Points Memo recently: "My position is I’m not voting for Hillary Clinton, and I’ll make a decision when I walk into the [booth] on Nov. 8."

Their motivation to flip-flop: Most politicians in all of these categories are risking a lot by recalculating their positions on Trump. Just because they've come back to him in one form or another doesn't mean they've won over any voters with that reversal.

But unlike their red state colleagues, lawmakers like Kirk and Heck don't just have to worry about their base next week. Nevada is a competitive swing state. Illinois is safely blue. Kirk in particular is going to need the support of more than a few Clinton voters.

Politicians in this group aren't really flipping or flopping, so much as acknowledging they're in a tough place with no good answers.

Once again, Trump has Hill Republicans in a no-win situation. This time, it's just seven days before an election.