Senate Minority Leader Chuck Schumer, a Democrat from New York.

Andrew Harrer | Bloomberg | Getty Images

Senate Minority Leader Chuck Schumer has made an offer to Senate Majority Leader Mitch McConnell on the parameters of an impeachment trial for President Donald Trump in that chamber that include calling former national security adviser John Bolton and acting White House chief of staff Mick Mulvaney to testify.

The offer, made Sunday, is intended as a signal that Democrats are seeking an evidentiary trial, and not intending to simply rely on the House investigation.

Schumer proposed that the Senate subpoena four people who are in close proximity to the president or are expected to have knowledge of the circumstances surrounding the delay of roughly $400 million in military aid to Ukraine: Robert Blair, senior advisor to the acting White House chief of staff; Mulvaney; Bolton; and Michael Duffey, associate director for national security at the Office of Management and Budget. Schumer proposed each side questions witnesses for four hours each.

House Democrats previously subpoenaed all four administration officials, who declined to testify.

More from NBC News:

Democrats blast GOP senators for signaling how they’ll vote in impeachment trial

Nadler: Anti-impeachment Democrat switching parties because he would lose primary

Schiff: I ‘hope to hell’ I’d impeach Obama if he did the same as Trump

Schumer added that Democrats “would of course be open” to additional testimony that has “direct knowledge” of security aid to Ukraine if House prosecutors or president’s lawyers were to request it.

McConnell has indicated his preference for a quick proceeding that wraps before witnesses are called, indicating that he hopes he has the support of 51 senators for a speedy resolution. In comments to Sean Hannity of Fox News last week, he said he and the president’s counsel are working closely, and that he hoped that in the Senate, there would not be “a single Republican who votes for either of these articles of impeachment.”

Democrats on Sunday pushed back at GOP senators who they said appeared to have pre-judged the proceedings.

“Senate Democrats believe strongly, and I trust Senate Republicans agree, that this trial must be one that is fair, that considers all of the relevant facts, and that exercises the Senate’s ‘sole Power of Impeachment’ under the Constitution with integrity and dignity,” Schumer wrote to McConnell Sunday. “The trial must be one that not only hears all of the evidence and adjudicates the case fairly; it must also pass the fairness test with the American people.”

Schumer also proposed that the Senate issue subpoenas on a “narrowly drawn” request that is “neither burdensome or time-consuming” of electronic communications and memoranda of relevant officials in the White House, OMB and State Department.

House Democrats’ impeachment investigation said that both security aid for Ukraine and a White House between Trump and Ukrainian President Volodomyr Zelenskiy were predicated on an announcement by Ukraine’s president of an investigation into former Vice President Joe Biden and his son Hunter Biden, who sat on the board of Ukrainian energy company Burisma.

Schumer and McConnell are expected to meet early this week to discuss the details of how a Senate trial would work. If no agreement is reached between the leaders, then the Senate would vote at each step of the process. Each vote would require the support of 51 senators.

Republicans control 53 seats in the chamber, but several Republicans — including Sens. Susan Collins of Maine, Lisa Murkowski of Alaska, and Mitt Romney of Utah — have indicated their preference for a full trial in the Senate.

Schumer proposed that the Senate proceedings begin on Jan. 6, 2020, with the swearing-in of Chief Justice John Roberts, who will preside over the proceedings — as well as the senators who will serve as jurors — occurring ‪on Tuesday, Jan. 7, 2020‬.

The House impeachment managers who would effectively act as prosecuting attorneys would be recognized ‪on Thursday, Jan. 9,‬ to present their case for a maximum of 24 hours, at which time the president’s counsel would be recognized for the same amount of time.

Schumer says his proposal is modeled after the resolutions setting up then-President Bill Clinton’s impeachment trial in 1999. However, there were two resolutions that year, with the second — which was adopted along party lines — deciding the witnesses and more controversial issues. Schumer has proposed passing one resolution.

As of late Sunday, McConnell had not yet responded to Schumer’s proposal.

Read More