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CNN —  

Senate Minority Leader Chuck Schumer made it clear in a letter to Majority Leader Mitch McConnell Sunday night that he prefers a Senate impeachment trial with witness testimony and new documents, a direct rebuttal to top Republicans who have argued in recent days that a shorter trial without witnesses would spare the Senate from becoming a partisan circus.

In the letter obtained by CNN, Schumer, a New York Democrat, called for at least four witnesses to testify, including 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 Office of Management and Budget official Michael Duffey.

“We believe all of this should be considered in one resolution. The issue of witnesses and documents, which are the most important issues facing us, should be decided before we move forward with any part of the trial,” Schumer wrote in the letter, adding that he would be “open to hearing the testimony of additional witnesses.”

The letter comes just days ahead of the House’s expected vote to impeach President Donald Trump, which would set up a trial in the Senate.

Schumer’s letter is the first public outreach between the leaders, who rank-and-file members on the Republican and Democratic sides have argued should sit down to hammer out the rules of the road. But Schumer’s letter casts doubt on whether the two leaders will be able to agree on any resolution that sets out impeachment floor proceedings. Ultimately, the Republican majority has the power to set the rules for a trial without Democratic votes, but it will require almost-complete GOP unity with just two votes to spare in their 53-member majority.

In an interview Monday morning with CNN’s John Berman on “New Day,” Schumer said the testimony from the four individuals is important because they “have direct knowledge of the facts, particularly in regard to the delay in the aid to Ukraine.”

“I don’t know what they’ll say. Maybe they’ll say something exculpatory about President Trump,” he said. “But for so many people who think that there are many Republicans who are saying ‘yeah, this looks pretty bad, but we need more evidence,’ this is the right evidence.”

But asked by Berman if Schumer would be OK with former Vice President Joe Biden’s son Hunter Biden being included as one of the “additional witnesses” his letter says he would be open to, Schumer wrote off the younger Biden’s potential testimony as “a distraction.”

Republicans “have not shown a single bit of evidence that Hunter Biden can answer any of these facts. He’s a distraction,” he said.

“This shouldn’t be for Democrats to bring in their favorite conspiracy theories and Republicans to bring in theirs. This is an august and solemn proceeding,” Schumer said.

McConnell spokesman David Popp said Sunday that “Leader McConnell has made it clear he plans to meet with Leader Schumer to discuss the contours of a trial soon. That timeline has not changed.”

The White House on Monday will review Schumer’s proposal for the Senate trial, an official involved in the matter said. Officials discussed the broad outlines of it Sunday, but are expected to do so more fully in person on Monday.

Responding during his CNN interview to the White House’s intention to review his letter, Schumer said he’s “glad” the administration’s plans differ from “tweets that just say … everything is perfect.”

“So let’s see. Let’s hope,” he said.

Schumer also laid out his preference for how long House managers and White House counsel would have to make their cases, cross-examine witnesses and give closing arguments. Schumer and McConnell have yet to meet to discuss the rules for the impeachment trial, which is expected to begin when lawmakers return from their holiday recess.

Schumer lays out his preference for a process

In his letter, Schumer suggested a detailed plan for how to run the Senate trial, including when it should begin and how long each side should have to make their case.

“I propose that pre-trial 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 wrote.

Schumer also outlined a plan in which each side would have 24 hours for “opening presentations and rebuttals” and 16 hours evenly divided for Republican and Democratic senators to ask questions.

In his letter to McConnell, Schumer also made it clear that he wants the Senate to subpoena additional documents that would shed light on why nearly $400 million in US military aid was temporarily withheld to Ukraine.

“This will be a narrowly drawn request limited to electronic communications, memoranda and related records of the relevant senior officials in the White House, Office of Management and Budget, and Department of State. Our understanding is that these records have already been collected by the White House counsel and counsel in the relevant agencies, so production in response to the Senate subpoenas should be neither burdensome nor time-consuming,” Schumer wrote.

Republican thinking so far

McConnell has said publicly that the Senate will begin its trial after the college football bowl games have ended, presumably the week of January 6. But, McConnell has remained vague on how long the trial will ultimately take or how it will be structured. He told reporters last week that senators would ultimately have two choices after House managers and the President’s counsel lay out their cases.

“It could go down the path of calling witnesses and basically having another trial or it could decide – and again, 51 members could make that decision – that they’ve heard enough and believe they know what would happen and could move to vote on the two articles of impeachment,” he said. “Those are the options. No decisions have been made yet.”

White House Counsel Pat Cipollone has remained in constant contact with McConnell about the impeachment trial, meeting with the majority leader as recently as Thursday afternoon.

“Everything I do during this, I am coordinating with White House counsel,” McConnell told Fox News host Sean Hannity last week.

CNN’s Ted Barrett, Phil Mattingly, Manu Raju, Kaitlan Collins and Devan Cole contributed to this report.