If you don’t think the bombshell revelation that John Bolton’s book will say Donald Trump wanted to withhold Ukraine aid until their government agreed to investigate Democrats has the potential to move the needle, consider the developments that ensued in its wake: Susan Collins suggested she would vote for witnesses, and Mitt Romney said it’s “increasingly likely” other Republicans would join them.

Meanwhile, Sen. Lindsey Graham abruptly canceled a press conference (later, he left open the possibility that he would subpoena Bolton’s manuscript, even as he remained opposed to having Bolton testify), and Pat Toomey proposed a “one-for-one” witness swap. By the end of the day Monday, Independent Sen. Angus King of Maine told NPR that he expects as many as 10 Republicans to vote for witnesses.

That’s not to say that everybody is suddenly changing their tune. Newly installed Sen. Kelly Loeffler of Georgia criticized Romney for his apostasy, saying he wants to “appease the left by calling witnesses who will slander Trump.” Rep. Mark Meadows, one of Trump’s impeachment surrogates, predicted there would be political ramifications for people like Romney. And when asked why Bolton shouldn’t testify, Sen. Ted Cruz chose, instead, to go on a diatribe about Hunter Biden.

To put it simply, Republicans are being torn and squeezed. A microcosm of this could be seen on Fox News, where Chris Wallace and Katie Pavlich publicly bickered on air about the Bolton controversy.

The problem with not allowing Bolton to testify is that it’s an absurd and indefensible stance. The problem with allowing Bolton to testify is that, even if the testimony, itself, isn’t damning, it could also snowball. I mean, if Bolton testifies, then why not Don McGahn or Rudy Giuliani or Mick Mulvaney or Mike Pompeo—especially if Bolton reveals something that might implicate them?

As such, voting to allow Bolton to testify—a vote that should be an obvious “yes” for anyone who really wants to get to the bottom of things—is high-stakes, because it could actually snowball and, you know, get to the bottom of things.

And getting to the bottom of things is the last thing Republicans want.

Not surprisingly, as Republicans are squeezed, the people feeling the pinch the most are those vulnerable senators who are up for re-election in 2020.

“ The problem with not allowing Bolton to testify is that it’s an absurd and indefensible stance. ”

If Republicans like Collins and Arizona Sen. Martha McSally and Colorado Sen. Cory Gardner and North Carolina Sen. Thom Tillis thought they could finesse this—thought they could “sort of” defend Trump and also sort of maintain their dignity—they were sorely mistaken.

They can have one or the other, but they cannot have both.

Making matters worse, it is entirely possible that these vulnerable Republicans will lose their seats and lose their reputations, all in one fell swoop.

Think about how much they have to lose. Now, to some, it might be palatable to trade your dignity for getting elected. Likewise, it might be palatable—a badge of honor, even—to lose an election because you stood on principle. Trump (and Bolton) have put Collins and McSally and Gardner and Tillis into a very, very unenviable spot.

According to a Fox News poll, half of Americans say Trump should be removed (that same Fox News poll shows Trump losing to six different Democrats in 2020).

There’s also the fact that revelations will likely keep leaking out after impeachment. Remember Lev Parnas? Do you really believe this Bolton revelation will be the last shoe to drop?

Indeed, the attorney for Lev Parnas is suggesting he has more recordings of Trump.

Senate Republicans are being squeezed like never before. This impeachment trial just got a lot more interesting.