Washington (CNN) House Democrats and White House officials are engaged in active preparations for the high-stakes trial of President Donald Trump, the latest sign that there's a widespread belief that it will still occur despite the bitter standoff that has left the proceedings in limbo.

Staff for key House committees, in consultation with Democratic leaders, are expected to work over the holiday recess to prepare for a trial in the event it starts early in the new year, according to two sources with knowledge of the work.

House Speaker Nancy Pelosi has yet to choose her team that will argue the case before the Senate, but Democratic sources say that it is expected to be led by House Intelligence Chairman Adam Schiff of California and House Judiciary Chairman Jerry Nadler of New York. Pelosi is expected to select members who represent the diversity of her Democratic caucus, but she's said she won't name the impeachment managers until the Senate details the scope of its trial.

The White House counsel's office, also, is privately preparing for a trial that could start in early January, and is in regular talks with Senate Majority Leader Mitch McConnell and his senior staff over how the trial would play out.

The uptick in moves underscore the reality that Trump will almost certainly get the trial he's been demanding, even though some House Democrats have urged Pelosi to indefinitely withhold the articles until McConnell agrees to a "fair" trial. McConnell, himself, said it would "be fine" if Pelosi never submitted the articles and a trial didn't consume the Senate.

The House needs to vote on naming the impeachment managers before the articles are sent over, Democrats say. The earliest House vote would occur on January 7, meaning the likely earliest start date of a Senate trial is January 8, assuming the partisan standoff has been resolved.

On Friday, White House counsel Pat Cipollone and Eric Ueland, the White House legislative affairs director, scouted out the locations in the Senate over where the trial would take place, something Ueland called a "good, straight-forward walkthrough." The tour was led by McConnell's top aides, and the White House officials also dropped into the GOP leader's office as well for a "brief conversation."

Sources in both parties believe that the standoff will ultimately be resolved, and a January trial still remains a serious likelihood, despite the fight over the scope of the trial.

McConnell and Senate Minority Leader Chuck Schumer are at an impasse over the rules for a trial, with Schumer wanting a deal struck up front on witnesses and documents and McConnell saying those decisions should come later and they should agree to just the nuts-and-bolts of the trial initially.

Schumer wants the Senate to hear from witnesses who were blocked by Trump -- like acting White House chief of staff Mick Mulvaney and former White House national security adviser John Bolton -- and is demanding documents that the White House withheld from the House. But McConnell says that the Senate is not on a mission to find new facts that the House Democrats did not pursue, saying they should have went to court.

So far, many Senate Republicans are siding with McConnell's stance, even those up for reelection in 2020 like Sen. Joni Ernst of Iowa.

"No, no," Ernst told CNN when asked if she wanted the Senate to hear from Mulvaney and Bolton. "They should have been heard from over in the House."

GOP Sen. Susan Collins, who faces a tough reelection in Maine, declined to say if she backs McConnell's position, saying, "I hope the two leaders can get together and work out an agreement."

The Senate would need to vote on a rule to establish the procedures of the trial; it remains to be seen whether McConnell seeks to advance such a rule with Republican votes only if Schumer declines to sign on.

It's still an open question which House Democratic lawmakers will prosecute the case in the Senate as impeachment managers, which will be selected by the speaker, though she is expected to name Schiff and Nadler, who chair the two committees that spearheaded the impeachment proceedings, as the leaders of the impeachment manager team.

Sources involved in the conversations also believe that Pelosi is looking to select a team that reflects her caucus. Among those being discussed are Rep. Val Demings of Florida, who sits on both the Intelligence and Judiciary committees and is an African-American woman. California Rep. Zoe Lofgren, a senior member of the Judiciary Committee who has experience from the Clinton impeachment, is also seen as another likely candidate.

Others expected to be on the short list include Reps. Hakeem Jeffries of New York, an African-American man on the Democratic leadership team and Raja Krishnamoorthi, an Indian-American man who sits on the House Intelligence Committee. Reps. Jim Himes of Connecticut, Eric Swalwell of California, Jamie Raskin of Maryland and Jackie Speier of California, also are considered to be on the short list, as is Rep. Joaquin Castro, who sits on the House Intelligence Committee.

But Democrats say Pelosi has not made any final decision, especially because she doesn't know the makeup of the trial. And she has not informed her colleagues who she is expected to name.

"If the Senate decides we're doing to have a full-blown trial with witnesses and cross examination, that might suggest a certain set of individuals with a certain skill set," said Rep. David Cicilline of Rhode Island. "If instead, the Senate is going to limit it to some legal arguments or some constitutional arguments, that may suggest another set of managers."

The sources say if the Senate is expected to hold a short trial with no witnesses, there will likely be a more limited team. A longer trial would likely to lead to a more robust team.