And so it comes down to Lisa Murkowski in the end. Will the vote on witnesses end in a 50-50 tie, or will Republicans have a narrow majority to carry the day toward a swift conclusion of Donald Trump’s Senate trial? Earlier this morning, CNN’s Manu Raju reported that Mitt Romney had decided to vote for witnesses and documents to extend the House investigation:

.@MittRomney will vote for the motion today to call for new witnesses and documents, an aide tells CNN’s @mkraju

— Jake Tapper (@jaketapper) January 31, 2020

Romney’s spokesperson later confirmed that Romney wants to hear from John Bolton in particular:

For those asking: As @SenatorRomney has said, he wants to hear from Ambassador Bolton, and he will vote in favor of the motion today to consider witnesses.

— Liz Johnson (@LJ0hnson) January 31, 2020

SEN. MITT ROMNEY indicated Friday that he will vote to allow additional witnesses and evidence in President Donald Trump’s impeachment trial.

Liz Johnson, a spokeswoman for the Republican senator from Utah, confirmed his support for a vote that would allow new documents to be introduced and new witnesses to testify, stating that he is specifically interested in hearing from former national security adviser John Bolton.

That sets up an interesting focus on Murkowski, whose constituency in Alaska is only somewhat Trump-enthusiastic, where Trump got 52.8% of the vote in 2016. (Hillary Clinton only got 37.6%, though.) She’s gotten crossways with the Senate Republican caucus more often than Romney has, helping to tube the GOP’s ObamaCare repeal in 2017 and voting against Brett Kavanaugh’s confirmation in 2018. Romney’s rebellions have usually been more rhetorical than substantive, although they’re more focused on Trump, too.

Buried in a largely fawning profile of Romney in the New York Times, thanks to his position on witnesses, is the assessment of his Republican colleagues. It’s not complimentary, and it’s not likely to improve this weekend:

Senator David Perdue, Republican of Georgia, likened Mr. Romney to “Jeff Flake on steroids,” referring to the former Arizona Republican and frequent critic of Mr. Trump who retired last year from the Senate. Senator Kelly Loeffler, Republican of Georgia, who was recently appointed to the Senate by that state’s governor — over the objections of the White House — tried to score easy points with Mr. Trump by ambushing Mr. Romney (roughly the Senate equivalent of the new inmate picking a fight with the biggest dude on the cellblock).

“My colleague @SenatorRomney wants to appease the left by calling witnesses who will slander the @realDonaldTrump during their 15 minutes of fame” tweeted Ms. Loeffler, who along with her husband had been a major donor to Mr. Romney.

Will Murkowski sign on to Romney’s initiative? Or has Mitch McConnell already managed this vote to allow Susan Collins off the hook and account for Romney’s position? I’d bet on the latter, but the former wouldn’t exactly surprise me, either.

Update: A 50-50 tie would almost certainly have the same impact as 51 votes against, but it sets up a food fight over whether John Roberts could cast a tie-breaking vote. Mitch McConnell won’t want that, and John Roberts really won’t want that dropped in his lap either. Murkowski might be convinced that it’s better to avoid that question and vote with the caucus on that basis alone.