From endorsing to un-endorsing and back again, here's a look at the Republicans who say they can no longer endorse Trump, but can still vote for him. (Jenny Starrs/The Washington Post)

Nineteen days ago, Rep. Jason Chaffetz (R-Utah) was so over Donald Trump.

"I'm out. I can no longer in good conscience endorse this person for president," Chaffetz said the day after The Washington Post revealed Trump's 2005 "Access Hollywood" tape. The breaking point, Chaffetz went onto say, was that he couldn't look his 15-year-old daughter in the eye and talk about what the GOP presidential nominee said: "It is some of the most abhorrent and offensive comments that you can possibly imagine."

That was 19 days ago. Now, he's — well, here's where Chaffetz stands on Trump as of Wednesday night:

Chaffetz may be trying to clarify that just because he's not supporting Trump doesn't mean he's not voting for him. But that's politics-speak for having it both ways. Any reasonable reading of the situation is that Chaffetz has spun a full 180 on Trump in a matter of weeks. Why? Why would a House Republican in a safe seat risk political ridicule (warning: strong language in that link) to awkwardly half-embrace his nominee, less than two weeks before a presidential election where said nominee looks like he'll lose?

The answer, of course, likely comes down to politics.

1) Hillary Clinton. Notice who else Chaffetz mentioned in that tweet: HRC, or Hillary Rodham Clinton. Chaffetz also happens to be the chairman of the highly political House Oversight Committee, and as such he is one of the most recognizable and political members of the House GOP. It's a job he gets a lot of press for, like Wednesday, when my colleague David Weigel reported that Chaffetz is planning an investigation — potentially years-long — into Clinton's use of a private email server as secretary of state, should she become president.

There's not much House Republicans can do legally to punish Clinton — but there is damage they could do to her politically. And in this partisan world, think of Democrats' and Republicans' fortunes as an inverse relationship: What's bad for one is good for the other. Chaffetz is in a position to be the guy who goes after a sitting president — an unpopular one at that, if public opinion polls this campaign tell us anything — for one of her most vulnerable problems.

But being the Clinton agitator gets much harder when you didn't vote for her opponent.

2) His political future. Soon this election will be over, and intra-GOP political maneuvering begins in earnest. Chaffetz is already in a high-profile job, but he clearly has bigger ambitions: When former House speaker John A. Boehner (R-Ohio) left last year, Chaffetz announced a run for speaker. (He dropped out after Paul D. Ryan got in.) And no matter how much members of Congress may dislike their party's presidential nominee, voting for that nominee is a minimal requirement to move up the hierarchy. Especially when Chaffetz's route includes going after the Democratic nominee.

"One thing that unites Republicans — and we are a Republican state — is distaste for Hillary Clinton," Chaffetz told Weigel this week. "I've said what I've said. Look, I originally endorsed Marco. If my endorsement meant anything, Mitt Romney would be president. I endorsed Mitt Romney. That didn't happen. I endorsed Marco Rubio. That didn't happen. I endorsed Trump, then I withdrew my endorsement. So I'm done telling people who to vote for."


House Oversight and Government Reform Committee Chairman Rep. Jason Chaffetz (R-Utah) (AP Photo/Brett Carlsen)

Chaffetz isn't alone; he joins a growing caucus of other high-profile Republicans who have since taken back their un-endorsement of Trump. Sen. John Thune (S.D.), the No. 3 in the Senate, is one prominent example. Most recently, Sen. Mike Crapo (R-Idaho) appeared to rescind his un-endorsement. Sen. Deb Fischer (R-Neb.) is another prominent endorse/un-endorse/re-endorser.

The confusion these "unsupportive endorsements" engender is likely a feature, not a bug — a reflection of the fact there really is no good answer Hill Republicans can give on Trump. Most are in a can't-live-with-him/can't-live-without-him situation: They can stay with Trump and risk alienating the one-third or so of their party who have a negative opinion of the nominee; they can ditch Trump and risk alienating their base; or they can attempt a mix of both, and risk political ridicule.

With less than two weeks to go, Chaffetz has opted for Option C. He may not be the last.