(UPI) — Senate minority leader Chuck Schumer said Democrats want to hear from four administration officials during the Senate’s forthcoming impeachment trial of President Donald Trump.

In a letter to Senate majority leader Mitch McConnell, R-Ky., Schumer said the Democrats want White House Chief of Staff Mick Mulvaney, former Nation Security adviser John Bolton, Senior White House Chief of Staff Advisor Robert Blair and National Security Associate Director Michael Duffy to be subpoenaed to testify before the Senate.

He said the Democrats would be open to hearing from additional witnesses with knowledge concerning the delay of security funds to Ukraine in exchange for the country investigating Trump’s political rival former Vice President Joe Biden and his son Hunter Biden.

“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,” said Schumer, D-N.Y. “This 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.”

He also proposed for pre-trial housekeeping to begin Jan. 6, for chief justice and senators to be sworn-in Jan. 7 and for House mangers to make their presentations Jan. 9, which would be followed by the presentation by the president’s counsel.

Senators would have eight hours to question each side followed by a period of six hours equally divided between the House managers and the president’s lawyers for final arguments that would be followed by a 24-hour period for senators to deliberate before voting on the articles of impeachment, Schumer proposed.

Democrats also proposed for the Senate to subpoena documents regarding the delay in the dispersal of funds to Ukraine. He said the electronic communications, memoranda and records have already been collected by the White House counsel “so production in response to the Senate subpoenas should be neither burdensome nor time-consuming.”

“We believe this proposal … will allow for a trial in which all of the facts can be considered fully and fairly, and in which final votes can be taken within a reasonable period of time, without any unnecessary delay,” Schumer said. “Conducting the trial according to this plan will also allow the public to have confidence in the process and will demonstrate that the Senate can put aside partisan concerns and fulfill its constitutional duty.”

The letter comes as the Democrat-controlled House is expected to vote later this week on two articles of impeachment charging Trump with abuse of power and obstruction of Congress.

McConnell has said that he will take his “cues” concerning the trial from the president’s lawyers and hopes the trial will be short.