(CNN) The Senate impeachment trial has entered perhaps its most fluid phase -- one where the White House is still technically presenting its defense, but senators in both parties are maneuvering for what comes next.

New revelations seemingly appear daily, all as senators attempt to structure their questions for the looming question-and-answer period and, of course, figure out how they will vote on whether to proceed to consider subpoenas for witnesses and documents. As of Tuesday morning, neither of those phases had definitive outcomes -- and they are both coming soon.

The bottom line at this point in time is that 51 votes in favor of moving to consider witnesses and documents do not exist, according to multiple high ranking GOP aides and officials. That doesn't mean they won't at some point, even some time soon, but the reality is many GOP senators are keeping their cards close, even from leaders. Again, things are fluid.

What to watch

A GOP press conference at 11:30 a.m.

Senate closed-door party lunches around noon

Senate Impeachment Trial of President Donald J. Trump gavels into session at 1 p.m.

What to read

This Jeremy Herb, Manu Raju, Lauren Fox, Betsy Klein piece is just a really sharp breakdown of what was a pretty crazy day.

Something Republicans are aware of

The Bolton revelations likely won't be the last "bombshell" or development related to the allegations at the center of this trial. And there will almost certainly be more after the trial ends, whenever that may be. It's been a key point several Democratic senators have quietly made to their GOP colleagues, CNN is told. Basically, they're arguing, "You don't want to be on the side of looking like you shut down a trial early when this stuff comes out."

So what's the schedule?

A GOP official tells CNN the White House team does not plan to use all of its remaining time in its third and final day to present its argument. Another person familiar with what to expect says that the arguments will last about two hours.

Ostensibly, Senate Majority Leader Mitch McConnell could move to the question-and-answer period as soon as the defense team yields back. According to a GOP source, however, the plan is to start the Q and A on Wednesday, but that also remains fluid. (Seeing a theme here?) It will largely depend on how long the White House goes and how senators are feeling about pushing forward.

When is the vote to proceed to witnesses?

Sen. John Thune told CNN's Ted Barrett the vote on whether or not to proceed to consideration of subpoenas for witnesses and documents will likely take place Friday or Saturday. That would seem to imply the question-and-answer period won't begin until Wednesday, but stay tuned.

When is the final vote?

We're just trying to get through Tuesday, man, relax.

But seriously, we just don't know.

The question-and-answer period is allotted 16 hours, and Democrats have made clear they plan to utilize the whole thing.

Then there will be four hours of debate, equally divided, between the House managers and White House counsel on whether to move to consider witnesses and documents.

Then the Senate could, technically, move into close session for deliberations, though nobody is sure if that will occur.

Then they will vote on witnesses.

How that vote comes down dictates your choose-your-own-adventure timing for the final vote. In other words, nobody knows.

The mood inside the GOP conference

Contrary to many of the public comments from GOP senators on Monday saying nothing changed (or really mattered) with The New York Times story on former national security adviser John Bolton's manuscript, Republicans were very unsettled. Many were angry. Things were, in the words of one Republican senator last night "a bit dicey there for a couple of hours" in terms of how the conference was going to respond.

But several GOP senators and aides said the White House presentations on Monday helped halt a potential scenario where a handful Republicans moved sharply toward witnesses, bringing them, at least for the moment, back in line with preferred path of the White House and GOP leadership.

Again, that doesn't mean it will hold for the duration, but for the moment, the large majority of the conference was, in the words of that senator, "reassured" by the presentations.

So I asked that senator: "Is that because senators in your conference are just looking for any reason to be reassured or where the presentations actually that good in your mind?"

GOP senator: "Yes."

McConnell's message

"Take a deep breath."

That was what McConnell told his conference in their closed-door lunch on Monday as he attempted to address the anxiety from the Bolton manuscript, according to several people in the room.

The basic message was to let the process play out. The rules allow for a witness vote later in the process, but don't make any decisions or declarations until GOP senators hear the entirety of the White House presentation and have an opportunity to ask questions.

The message appeared to have its effect for now, but make no mistake, things were bumpy yesterday inside the conference.

Romney's message

Just as McConnell delivered his message behind closed doors to the Republican conference, Sen. Mitt Romney delivered one of his own, according to several people in the room. Pointing to the Bolton reporting, Romney made clear the conference should be open to hearing from witnesses. It's something Romney, two senators tell me, has been quietly pitching to senators in one-on-one conversations for several days.

It's tough to know whether those efforts will bear fruit for Romney, but he's absolutely working to make it happen.

Behind the witness trade proposal

Let's make something very clear: the idea of a "one-for-one" deal on witnesses, i.e. one Democratic witness for one Republican witness, has been pinged around the GOP conference for weeks.

Sen. Ted Cruz pitched it to McConnell in a private meeting several weeks ago. Sen. Mike Braun of Indiana had been talking to Cruz about it for several weeks.

The development on Monday was Sen. Pat Toomey , a Pennsylvania Republican, voicing support for the idea in front of his colleagues, which was a window into some of the work he's been doing behind the scenes as Republicans try to navigate the process.

But the idea for a "deal" is not one embraced by the White House or GOP leaders. (In fact, one senator told me Toomey's comments were not well received inside the conference.)

Instead, it serves as a bit of a "break the glass" proposal if it becomes clear at least four Republicans are going to vote with Democrats on witnesses.

Remember, if it looks like McConnell is going to lose the witness vote, he will move quickly to take control of the process of what comes next. And what comes next has the potential to get spicy real quick.

A reminder: the witness and documents vote is solely on whether the Senate will move to consider witnesses and documents. It doesn't mean witnesses and documents will be subpoenaed. At all. In fact, every standalone vote may then fail. Why? Well every resolution for a specific witness or document set can be amended, meaning there are ways to attach poison pills to things that will gum up the intentions of Democrats quite quickly. That's what I mean when I say things can get spicy real quick.

The vote breakdown

Romney and Sen. Susan Collins, long the two Republicans most likely to vote to consider witnesses, moved more firmly in that direction on Monday and are considered sure "yes" votes by Republicans.

Sen. Lisa Murkowski told reporters she remains "curious" as to what Bolton would say and has also signaled openness to witnesses, but also very clearly hasn't made up her mind. It's frustrating to many, but by all accounts she is legitimately letting the trial play out for the time being.

Others Senate Republicans to watch, per multiple senators and aides:

Toomey

Sen. Rob Portman of Ohio

Sen. Lamar Alexander of Tennessee

Sen. Jerry Moran of Kansas

The question-and-answer period

People haven't been paying much attention to this outside the chamber, but inside this has garnered a significant amount of attention. Senators started presenting their proposed question to leadership throughout the day Monday. This was, in fact, the primary purpose of the closed-door GOP lunch -- discussing this next phase of the trial. Democrats did the same, I'm told.

Notably, two senators told me there have been several bipartisan "pairs" that have formed to join together for specific questions. This was done during the Clinton impeachment trial and doesn't necessarily connote some grand significance, but the tone and tenor of a bipartisan question may carry more weight in how it's viewed and received.

What Democrats will be talking about for days to come

GOP Sen. Joni Ernst of Iowa, shortly after the White House team's presentation attempting to tie Vice President Joe Biden and his son to Ukraine corruption allegations, saying the thing Republicans have taken pains not to say, and all on camera:

"Iowa caucuses are this next Monday evening. And I'm really interested to see how this discussion today informs and influences the Iowa caucus voters, those Democratic caucus goers. Will they be supporting Vice President Biden at this point?"