Some ask why “moderate” Republican senators have largely refused to criticize Mitch McConnell’s scheme to undermine the Constitution by preventing witnesses from testifying during Donald Trump’s upcoming removal trial. But it’s no mystery.

In fact, McConnell intends his machinations, first and foremost, to aid swing-state senators, particularly those facing re-election in 2020, like Maine’s Susan Collins, Arizona’s Martha McSally, North Carolina’s Thom Tillis, Iowa’s Joni Ernst, and Colorado’s Cory Gardner. Those legislators are facing a stark choice: If they fail to excuse Trump’s criminal conduct, they’ll lose the support of their party’s Trump-loyal voters.

But if they vote to acquit after figures like Mick Mulvaney and John Bolton further implicate the president in a scheme to undermine the next election (and an ally under attack by Vladimir Putin’s Russia), they risk losing the support of most other voters. It is a dilemma of Republicans’ own creation, and it’s becoming more excruciating every day.

There’s a darkly humorous video, apparently recorded a number of weeks ago, of a hapless Marco Rubio rushing down the corridors, and riding the elevators, of the Capitol in an assiduous effort to avoid answering a Florida military veteran’s question: Was it OK for the president to coerce a foreign country to do his political bidding? But in his efforts at evasion, Trump’s home-state senator made a gaffe. There was no need for him to consider the facts before Trump was impeached, Rubio asserted, because: “We’ll have a trial... and... do nothing but hear the facts.”

Yet, of course, McConnell’s primary goal is not to hear the facts; on Dec. 13, the Senate majority leader forthrightly declared that he’s planning the “trial” of Trump in close consultation with the defendant; and his primary focus from the outset has been to ensure that the trial will not include any new witnesses or documents.

When House Speaker Nancy Pelosi said she planned to take her time in “delivering” the articles of impeachment to the Senate, while demanding that McConnell agree to conduct an actual trial, McConnell’s GOP colleagues initially chuckled. Some of them bragged off-the-record to reporters that Pelosi was out of her depth, and didn’t understand what a master of the Senate McConnell is, particularly when it comes to preventing things from happening in the upper chamber (other than the confirmation of extremist judges).

But it has since become increasingly clear that McConnell is the latest of many men of power in the GOP to underestimate both Pelosi, and to overestimate the tolerance of the American people for presidential criminality. Washington Republicans spent the days following the impeachment hearings focused on political maneuvering, and seemed to forget the virtually undisputed evidence of a massive criminal scheme directed by the president that had emerged before Congress.

Indeed, until recently, GOP senators appeared unperturbed by polling showing that seven in 10 Americans want to see a fair trial, in which the hidden witnesses are brought forth to testify under oath. Somehow Mitch would work his magic again, they apparently thought, and—thanks to his continuation of Trump’s stonewalling—the pseudo-trial would come and go quickly in January, allowing Trump’s scheme to force Ukraine to interfere with the upcoming election to fade into the background, even as Russia moves forward with its 2020 interference efforts. Indeed, even before the House voted to impeach the president, Trump stooge Lindsey Graham began openly bragging that he would treat the entire constitutionally mandated process as a “sham.”

But, even though Trump offers the nation a steady diet of lies, actual facts are stubborn things, and information about the president’s crime scheme has continued to emerge. None of the material that has dribbled and leaked out over the past couple of weeks materially changes the ugly story that witnesses like the grave Marie Yovanovitch, Bill Taylor, Fiona Hill, Alexander Vindman, and the smirking Gordon Sondland, revealed to the nation just weeks ago.

But the new facts confirm the scale and audaciousness of the president’s criminal scheme, as well as the radioactivity of the documents and witnesses that McConnell has joined Trump in seeking to embargo. For example, an email wrenched from the White House by the Center for Public Integrity shows that the White House formalized Trump’s freeze on security assistance to Ukraine on July 25, immediately after Trump held his extortionate call with that nation’s President Volodymyr Zelensky.

“ It is indeed a dilemma, but one of Republicans’ own creation, a product of their decision to do what it takes to maintain their party’s grip on power, regardless of the cost to the nation or its laws and Constitution. ”

And The New York Times reported that Defense Secretary Mike Esper, Secretary of State Mike Pompeo, and then-National Security Adviser John Bolton jointly urged Trump to release the aid last summer, only to be refused by a president who was determined to continue to pressure Ukraine to dirty up a political adversary. Meanwhile, the White House was secretly cooking up a version of the so-called unitary executive theory to justify Trump’s crimes so overreaching that it would, until recently, have given even Bill Barr pause; put simply, Trump’s acolytes contended Trump was free to violate a statutory mandate to deliver the congressionally appropriated aid because, well, he’s the boss.

The additional evidence highlights a fundamental problem with Trump/McConnell’s stonewalling strategy that GOP senators are only belatedly coming to recognize: The wall was breached months ago. Barr did his best to hide the whistleblower’s account of Trump’s Ukraine scheme, just as he had boxed up the evidence underlying the Mueller Report, but the attorney general’s effort failed when witnesses appeared, and told the truth, before Congress. In the wake of those revelations, it was as certain as the path of a boulder down a mountain that additional evidence of the president’s crimes would continue to come to light, whether or not McConnell succeeded in engineering a fact-free “trial.”

Republican legislators have fashioned a Hobson’s choice for themselves. On the one hand, they can accede to Trump and McConnell by violating their oaths and the Constitution, and voting to dismiss without hearing from the embargoed witnesses—and take a risk that their knuckling under to Trump ends with ignominious losses in the next general election.

On the other hand, GOP “moderates,” possibly joined by more independent colleagues, such as Lisa Murkowski and the soon-to-be retired Lamar Alexander, can vote to call figures like Mulvaney and Bolton, and even vote in favor of conviction—thereby inviting primary challenges ginned up by Trump himself.

It is indeed a dilemma, but one of Republicans’ own creation, a product of their decision to do what it takes to maintain their party’s grip on power, regardless of the cost to the nation or its laws and Constitution. If the trial ends up making the corrupting consequences of that choice clearer to the nation, then maybe justice will be done after all, regardless of whether further witnesses appear, or of Trump’s virtually certain “acquittal.”