Washington (CNN) Senate Republicans are starting to coalesce around the idea of a shorter Senate impeachment trial -- one that, contrary to President Donald Trump's stated desire, wouldn't include witnesses.

The layout of the Senate trial is still under deliberation and leaders have been clear that no final decisions about strategy or structure have been made, but in interviews over the last several days, GOP senators say they are beginning to see the benefit of keeping the process short, leaving out witnesses and instead, simply laying out the facts with a presentation from House managers and the White House.

"I would think the consensus would be let the House make their case, let the Senate make their case and then put forward a motion to vote," said Sen. Ron Johnson, a Wisconsin Republican.

That marks a shift from a few weeks ago when a number of Republican senators made clear they would go to great lengths to ensure that voters couldn't accuse them of cutting the process short. It was a position that tracked with the Trump White House, which has said publicly, and repeatedly, it wants to hear live testimony from individuals including Hunter Biden and the whistleblower.

As the House moves swiftly to a floor vote on impeachment, senators must grapple with what now looks inevitable: that they will act as a jury in a historic impeachment trial.

Many questions remain unanswered, however, about how exactly such a trial would proceed. The decision of whether or not to call witnesses could have a significant impact on the way the process unfolds.

A Republican senator granted anonymity to speak candidly about concerns within the GOP conference said that the President's desire to have a long trial with many witnesses could backfire.

The senator warned that for every witness called by the President's defense team who might testify in favor of the President, there could be another witness called by Democrats whose testimony could hurt him.

The senator specifically pointed to acting White House chief of staff Mick Mulvaney and former Trump national security adviser John Bolton as witnesses Democrats might try to hear from if Republicans call in Hunter or Joe Biden, the whistleblower or others.

The senator said the President's "urge for vindication" is understandable but "witnesses cut both ways. We wouldn't be the only ones who would be able to call witnesses."

'A pretty messy and unproductive process'

One Republican senator who has spoken to the President about the issue made clear that no strategic decisions would be made without the White House sign off, but said it wasn't impossible that the White House would sign off on the shorter trial.

As to Trump's view on the matter, the senator said only: "It depends on when you catch him."

A shorter trial is a position that tracks with the message Republicans senators, including Majority Leader Mitch McConnell, have privately conveyed to the White House over the last several weeks, according to several Republican senators familiar with the conversations.

The structure and rules of a potential trial have also been the subject of closed-door Senate GOP lunches for several weeks. More and more the view in the conference has started to shift, underscoring the desire to both avoid a messy process and clear the Senate floor for the chamber to work on other issues.

"Extending this for weeks on end and having lots of votes on motions to call witnesses, doesn't seem to me to be a good use of the Senate's time," Sen. John Thune, the second-ranked Republican in the chamber, told CNN..

Still, Republicans acknowledge nothing is settled or has even been fully debated at this point internally. The sheer number of unknowns -- including whether McConnell and Minority Leader Chuck Schumer can reach agreement on the structure of a trial and what that agreement, if reached, would entail -- make any firm conclusions about what's coming next an impossibility.

But after watching the House impeachment inquiry play out, the thinking is that calling witnesses would quickly devolve into a messy, contentious battle that would reveal intra-party schisms and eat up precious floor time in an election year.

For Republicans who hail from swing states, a drawn-out debate that forces them to decide whether to call the whistleblower or Hunter Biden to the Senate floor, could have political costs on either side. Voting against the President's wishes could cost them base turnout and a critical Presidential tweet. Voting to call people like the whistleblower or Biden could cost them independents.

"I think people are starting to realize that that would be a pretty messy and unproductive process," Johnson said of the idea of bringing in witnesses.

'I am not in the camp of calling a bunch of witnesses'

Republican Sen. Lindsey Graham, a close ally of Trump, on Wednesday appeared to throw cold water on the idea of calling a large number of witnesses during a Senate trial.

"There are people wanting to call (Secretary of State Mike) Pompeo, they want to call (Vice President Mike) Pence, they want to call Joe Biden, they want to call Hunter Biden. I am not in the camp of calling a bunch of witnesses, but that's just me," Graham told reporters. "I am in the camp of basing my decision based on the record prepared in the House."

"I think as an American, the best thing we can do is deep six this thing," Graham added. "Take the record that was prepared in the House and base an impeachment vote on if they get enough votes, use that same record to decide guilty or innocent, not call a bunch of people, you know that people dream of hearing from, like Pence, Pompeo, Joe Biden and Hunter Biden. There's a way to deal with that outside of impeachment."

GOP Sen. Mike Braun of Indiana predicted a Senate trial could be as short as 10 days and as long as four weeks.

"My opinion would be the shortest you move through this is 10 days to two weeks. And if it's belabored it might go three to four weeks. But if there is nothing new, I don't see how it can go into the long end of it," he said.

"I'd say keep it short and simple without truncating or shortening the basics that you need. Especially if there's no new information that comes forward," he added.

On witnesses, Braun said he respected Trump's desire to have exculpatory evidence presented at the trial but he cautioned that "witnesses would be a double-edged sword."

"We've heard him talk about a fully litigated defense in the Senate but I think once they get down to the strategy in the Senate, does that make sense? Does it turn into a circus? Where do you start and stop. How many witnesses?"

How a trial could unfold

Republicans are beginning to see the Senate impeachment trial in two parts. The first, the presentations from the House managers and the White House. Then, there would be a decision. Do senators need to hear witnesses? Or, would they rather take the offramp and vote.

McConnell laid out the two scenarios to reporters on Tuesday, making clear that no decisions have been made at this point. But he made two central points as he did.

First, if after the two presentations 51 senators are in agreement that the trial should come to an end, teeing up final votes on the two articles of impeachment, then that's all it would take to make it happen. With Republicans in control of 53 seats in the Senate, even if Democrats took the position that they wanted to push forward with votes to hear from witnesses like Bolton and Mulvaney, it would take only Republican votes to snuff that idea out.

Second, McConnell also reiterated his view that finding the 67 votes to actually remove Trump from office is, at least at this point, a virtual impossibility -- something that would underscore the argument for not delaying what Republican senators view as an inevitable acquittal.

"I would be totally surprised if there were 67 senators to remove the President," McConnell said. "That remains my view."

Sen. Shelley Moore Capito, a Republican from West Virginia, told CNN she doesn't know how she will feel after the presentations of evidence from both sides, but that she might be ready to vote without hearing witnesses.

There's also the issue of whether senators have reached the point where they simply want to move on after the presentations, given the trial essentially shuts down all other business in the chamber and requires senators to be present, and in their seats, six days a week without the ability to speak.

"I think at some point people just going to get real tired of this," said Sen. John Cornyn, a Texas Republican.

Asked if he would support moving forward with a vote without witnesses, Sen. John Kennedy, a Republican from Louisiana, wouldn't speculate how it shakes out.

"We haven't even agreed to the rules yet," Kennedy said.