Senate Minority Leader Chuck Schumer sent a letter to Majority Leader Mitch McConnell on Sunday that details the witnesses and timeline Senate Democrats would like to see in an impeachment trial in January. The House of Representatives is expected to vote on two articles of impeachment against President Trump this week.

"In the trial of President Clinton, the House Managers were permitted to call witnesses, and it is clear that the Senate should hear testimony of witnesses in this trial as well," Schumer writes.

Schumer proposes that Supreme Court Chief Justice John Roberts, who will preside over the Senate trial, issue subpoenas to four administration officials who were asked to testify in the House impeachment inquiry but did not appear: Acting White House chief of staff Mick Mulvaney, former national security adviser John Bolton, senior adviser to the Acting White House chief of staff Robert Blair and Michael Duffey, associate director for National Security, Office of Management and Budget.

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"We would of course be open to hearing the testimony of additional witnesses having direct knowledge of the administration's decisions regarding the delay in security assistance funds to the government of Ukraine and the requests for certain investigations to be announced by the government of Ukraine, if the president's counsel or House Managers identify such witnesses," Schumer added.

A source familiar with Mulvaney's legal strategy says he will still follow White House direction over whether to testify or not.

Schumer aides describe the letter as the first move to establish a bipartisan framework for the upcoming trial. It comes as some Senate Republicans, including McConnell himself, have been signaling to Mr. Trump they would prefer a speedy trial that does not involve calling any new witnesses.

In response, McConnell spokesman Doug Andres said the majority leader has made it clear to Schumer that he plans to meet soon to discuss the framework of a trial. "That timeline has not changed," Andres said.

"If you…believe the case is so slim, so weak that you have the votes to end it, that might be what the president's lawyers would prefer, and you could certainly make the case for making it shorter rather than longer," McConnell argued in an interview on FOX last week. "A lot of people would like to bring in Adam Schiff, Hunter Biden, Joe Biden. [But] I think I'm more inclined to agree with Senator Graham on this."

On CBS' "Face the Nation" on Sunday, Senator Lindsey Graham said he thinks "what's best for the country is to get this thing over with….So I don't need any witnesses."

"I am ready to vote on the underlying articles," he added.

Senate Democrats have argued that such an approach would prevent a full airing of the facts.

At a press conference in New York City on Sunday, Schumer said, "So far, McConnell has not come to me, and I'm worried that we won't get a fair trial where all the facts and all the truth comes out. I'm going to work very hard to get that done."

His letter proposes that "the Senate issue subpoenas for a limited set of documents" including "electronic communications, memoranda and related records of the relevant senior officials in the White House, Office of Management and Budget, and Department of State."

Those agencies refused to provide any documents to the House impeachment inquiry, which White House lawyers derided as a "sham." Senate Democrats believe it would be more difficult for the White House to justify stonewalling the Republican-led Senate.

On CBS' "Face the Nation" on Sunday, Senator Dick Durbin argued, "The bottom line is, if we are going to have an actual trial, we should consider evidence. And that's why I think Senator Schumer and Senator McConnell need to sit down and have an orderly, respectable process in the Senate."

Schumer's letter also lays out a proposed timeline for a Senate trial.

"Specifically, I propose that pretrial housekeeping measures be adopted on Monday, January 6, 2020; that the swearing-in of the Chief Justice and Senators occur on Tuesday, January 7, 2020; that after a period for preparation and submission of trial briefs, the House Managers be recognized on Thursday, January 9, 2020 to make their presentation for a period of not more than 24 hours, followed by the presentation by the President's counsel, also for a period of not more than 24 hours."

Schumer proposes each witness be questioned for no more than four hours by House Managers and four hours by the president's counsel.

The decision may end up coming down not to Schumer or McConnell but to all 100 senators. It would take a majority vote of 51 to cut the trial short without hearing from witnesses. Republicans currently hold a slim 53 to 47 majority, and a few Republicans — such as Utah Senator Mitt Romney and Maine Senator Susan Collins — may balk at the notion of a hasty trial.

In his letter, Schumer argues that his proposal is in line with historical precedent, most notably the impeachment trial of former President Bill Clinton in 1999. "These provisions are modeled directly on the language of the two resolutions that set forth the 1999 trial rules," he says. "The first of those resolutions passed the Senate by a vote of 100-0."