This has been updated with the latest news.

The holiday break is wrapping up, but there doesn’t seem to be an end in sight to the stalemate between House Democrats and Senate Republicans over how to hold President Trump’s Senate impeachment trial.

House Speaker Nancy Pelosi (D-Calif.) is withholding the articles of impeachment from the Senate and not naming House lawmakers to prosecute the case (called managers) until Senate Majority Leader Mitch McConnell (R-Ky.) agrees on parameters of a trial that she views as fair. “We cannot name managers until we see what the process is on the Senate side,” she has said. But McConnell has said that he’s working in “total coordination” with White House lawyers and that there is no such thing as fair in a political body, so why even try? “This is a political exercise,” he has said.

That means it’s a real possibility that Congress comes back next week and there is no Senate trial starting up soon, as expected. So how could this impasse end? Here are four possibilities, ranked from least to most likely.

4. There is no Senate trial — at least not in 2020

Could there just be no Senate trial to acquit or convict Trump?

This is a trial that Republicans never wanted in the first place. Not a single Senate Republican has said that they think Trump deserved to be impeached. “Fine with me,” McConnell has said about Pelosi holding back the articles of impeachment.

On Thursday, Sen. Josh Hawley (R-Mo.) said he’d be introducing something early next week that could lead the Senate to just not have a trial.

Or what if Democrats held back the impeachment articles and the naming of House prosecutors until Democrats won back the Senate in the 2020 elections? (Which, by the way, is a big risk. They’ll need to win in states that voted for Trump in 2016.)

Or what if McConnell decided to hold a trial without the articles, or without House Democrats as prosecutors? That’s really out there in terms of constitutional law, but everything about this impeachment process has been norm-breaking.

Why this might not happen: No Senate trial is the least likely option just because it’s so far-fetched. The consensus among legal experts is that the Constitution requires a Senate trial to happen after the House impeaches a president. Senators decide whether to acquit or convict the president on the impeachment charges (in this case, abuse of power and obstruction of Congress), and if they convict him, he’s removed from office.

3. Pelosi gets her way …

… And McConnell agrees at the outset to call witnesses.

Let’s pause to understand the mechanics of how senators set up this trial. Before the trial gets started, senators vote on the parameters. It takes a majority vote to approve the rules. But they can make a decision later to vote on whether to add witnesses, and The Washington Post has reported that McConnell is hoping that after hearing opening arguments from both sides, Senate Republicans will just want to vote and be done with the trial. (If all Senate Democrats stick together, it will take defections from four Republican senators to get a majority on board with anything.)

There have been a couple of pieces of news over the holidays that could give Pelosi and Senate Democrats even more leverage to get what they want in a Senate trial:

  • A federal judge threw out a lawsuit that former national security adviser John Bolton had said would determine whether he testified in the House’s impeachment inquiry. (The House impeached Trump without waiting for this suit to play out.) So now, Democrats could argue that the courts aren’t going to weigh in and that Bolton should be available to share what he knows.
  • Newly released emails from the White House and Pentagon have driven home key aides’ role in holding up military aid for Ukraine under still-mysterious circumstances, bolstering an argument by Senate Minority Leader Charles E. Schumer (D-N.Y.) that people such as Bolton and acting chief of staff Mick Mulvaney should testify in a Senate trial. “This new evidence also raises questions that can only be answered by having the key Trump administration officials … testify under oath in a Senate trial,” Schumer said in a statement Thursday.
  • Two Senate Republicans have expressed reservations about McConnell’s wishes for a purely political trial. Sen. Lisa Murkowski (Alaska) said she’s “disturbed” by it, and Sen. Susan Collins (Maine) said it’s “inappropriate” for any senator to prejudge.

Why this might not happen: It’s hard to see McConnell suddenly acquiescing to Democrats’ demands. It might sound cynical, but his mind-set is that he has a right to hold a trial however a majority of senators want, and that probably means however Republicans — and Trump — want.

2. McConnell gets his way …

… And he gets to hold the trial in a way that benefits Trump. McConnell is not out there saying exactly how he wants that to look, but we could assume that means a quick one without any witnesses or new evidence.

McConnell isn’t ruling out witnesses. But it appears he’s doing everything he can to avoid calling them, so as to prevent people with potentially damaging information on Trump and Ukraine, such as Mulvaney or Bolton, from testifying. McConnell also probably doesn’t want Trump to get his preferred way and have his attorneys cross-examine people such as former vice president Joe Biden or the whistleblower whose complaint is at the heart of the impeachment inquiry.

Why this might not happen: Although McConnell controls the majority in the Senate, this isn’t the likeliest option, because there’s an argument that he and Trump want the trial more than Democrats do.

Trump sees a trial in the Republican-controlled Senate as a chance to exonerate himself and maybe even to undermine the Democratic-led House impeachment. A GOP Senate aide told The Fix that it’s possible that some red-state Senate Democrats vote to acquit Trump, which would go a long way toward Trump being able to argue that opposition to his impeachment was technically bipartisan. (Two Democrats in the House voted against impeaching him.)

1. They come up with some kind of compromise

But what would that look like, given the differences between the two sides over witnesses? Josh Chafetz, a constitutional expert at Cornell Law School, said that there are smaller things on which senators could compromise to get the trial started and that the big thing can be addressed later on. They could compromise on how long the trial should be (two weeks? six weeks?) and whether new evidence can be presented.

“In other words, witnesses/no witnesses isn’t a binary: there are a lot of smaller procedural trade-offs that can be made,” Chafetz wrote in an email to The Fix.

That still doesn’t solve the broader problem of how to break the impasse between Pelosi and McConnell over witnesses, but it’s a start.