The impeachment trial is approaching a volatile and unpredictable stage as President Donald Trump's defense team wraps up its opening argument, and the outcome of a looming vote on whether to call witnesses remains uncertain.
Senate Republicans feel they weathered the storm on Monday in the wake of revelations from former national security adviser John Bolton's draft book manuscript that Trump told him US security assistance to Ukraine was conditioned on investigations into Democrats, including the Bidens.
The Bolton developments jerked the conversation in the Senate over witnesses into a new direction. But several GOP senators and aides said the White House presentations on Monday helped halt a potential scenario in which a handful Republicans moved sharply toward wanting to hear from witnesses.
Instead, Senate Republicans are, for now, in line with preferred path of the White House and GOP leadership to defeat a witness vote and bring the trial to a close.
But the situation in the Senate Republican conference remains fluid. Two Republican senators, Mitt Romney of Utah and Susan Collins of Maine, have signaled they want to hear from witnesses, including Bolton. Sen. Lisa Murkowski of Alaska says she is "curious" about Bolton's testimony.
Still, there's no sign of a fourth GOP senator expressing support for witnesses at this point, though several Republicans remain on the fence.
"I think the facts are all out there," said Senate Majority Whip John Thune of South Dakota. "I don't think that anything that he's going to say changes the facts ... I think people kind of know what the fact pattern is."
An administration source familiar with White House conversations with Republican senators said that the vote on witnesses is still tough, and that they are "working it hard."
While Senate Majority Leader Mitch McConnell told his conference to "take a deep breath," Romney made a pitch to his colleagues for witnesses on Wednesday.
"I think each individual is going to make their own decision and they're not, I don't think they're all settled, as a group, or as individuals as to exactly how they're going to vote," Romney said Tuesday.
Romney also said the an idea that's percolated in Republican circles in recent weeks — that if they're forced to hear from witnesses, it has to be reciprocal — "has some merit."
The question of witnesses will be addressed later in the week. First, the President's defense counsel will wraps their opening argument on Tuesday with presentations from Pat Cipollone and Jay Sekulow, according to a source familiar with the matter. It's expected to be a short day of roughly two hours, though the Senate could begin the next phase where senators ask questions of the two sides.
One Republican senator said a majority of the conference was "reassured" by the defense team presentations on Monday, and senators particularly highlighted constitutional lawyer Alan Dershowitz's argument.
"I think he probably gave a lot more peace of mind to people that were wanting to see how to sort through it, when he made a strong case that each article was ill-founded," said Sen. Mike Braun of Indiana. "And the key thing ... was even if Bolton's revelation in its full form was true, is that impeachable in your opinion? He said no because it imputes motives."
Democrats are continuing to call for Bolton to testify and the Senate to seek notes from Bolton, and Democratic aides say they expect to hammer that point home during the question-and-answer period, which could last up to 16 hours over two days.
"What I've not heard from any of my Republican colleagues is what's the reason not to see John Bolton and how stupid are we all going to look if his book comes out with extraordinarily relevant information 60 days from now and this proceeding is over," said Sen. Mark Warner, a Virginia Democrat.
Democrats also have another goal in mind with the question-and-answer sessions: Defend former Vice President Joe Biden from what they say are unsubstantiated false attacks on the former vice president from the defense team on Monday.
"Among the questions that did that I've been working on with the with my staff are questions just to make it clear what Joe Biden's role has been in this. This stuff that somehow he was involved with this conspiracy — that's a distraction, that's a bright shiny object," said Sen. Tom Carper, a Delaware Democrat.
With the Bolton revelations fresh in their minds — and cognizant that more developments still could be coming this week — Republicans are also drawing up other contingency plans for dealing with the former national security adviser's allegations.
After GOP Sen. James Lankford of Oklahoma proposed a plan that would make Bolton's manuscript available to senators in a classified setting, Sen. Lindsey Graham, a South Carolina Republican, took to Twitter on Tuesday morning to jump on the idea.