By Kasie Hunt, Frank Thorp V, Leigh Ann Caldwell and Dareh Gregorian
WASHINGTON — The Senate impeachment trial of President Donald Trump — only the third in U.S. history — is scheduled to get fully underway Tuesday, with Democrats and Republicans potentially clashing over whether to call witnesses.
The proposed rules for the trial, which Senate Majority Leader Mitch McConnell, R-Ky., released Monday evening, are similar but not identical to the format of President Bill Clinton's impeachment trial in 1999. McConnell's rules would set aside up to four hours of debate, equally divided between both sides, on whether there should be subpoenas for witnesses or documents, and then the full Senate would vote on the issue.
Senate Minority Leader Chuck Schumer, D-N.Y., could seek to amend the rules Tuesday to ensure that his side can call witnesses, a process that could take several hours and could even include closed-door debates. McConnell maintains that he has the votes to largely follow the Clinton blueprint regardless of Democratic maneuvering. Once the rules are approved by a majority, opening arguments are expected to begin this week.
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Here's everything else you need to know about the Senate impeachment trial.
Technically, it already has — the trial officially began Thursday, when Chief Justice John Roberts and senators were sworn in and the lead House manager, Adam Schiff, D-Calif., read the articles of impeachment on the Senate floor charging Trump with abuse of power and obstruction of Congress.
The House managers — essentially prosecutors — spent the weekend submitting briefs laying out why the Senate should remove Trump from office. The president's newly announced legal team submitted filings explaining why he should be acquitted.
The trial resumes at 1 p.m. ET Tuesday, when the two sides will butt heads over the organizing resolution. Opening arguments will begin after the Senate votes on the resolution, likely Tuesday or Wednesday.
Roberts will preside over the trial, but his role is more limited than that of a judge in a courtroom. He would rule on evidentiary questions or pass them along for the Senate to vote on. The Senate can override Roberts' decisions with a majority vote.
The entire Senate is the jury, but it also has some judge-like powers. In addition to voting on procedures and evidence, senators can submit objections to Roberts. They're not allowed to directly question attorneys for the two sides, but they can offer questions to Roberts, who will read them.
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House Speaker Nancy Pelosi, D-Calif., last week announced the seven House Democrats who will act as the case managers: Schiff, the lead manager; Jerry Nadler and Hakeem Jeffries of New York; Jason Crow of Colorado; Zoe Lofgren of California; Val Demings of Florida; and Sylvia Garcia of Texas.
Trump's defense team is being led by White House counsel Pat Cipollone, and Trump's personal attorney Jay Sekulow has a leadership role, as well. The president added some surprising names to his team, including former independent counsel Ken Starr, who investigated Clinton, and the famed defense lawyer Alan Dershowitz.
Also on board are former Florida Attorney General Pam Bondi and Robert Ray, who succeeded Starr as the Clinton independent counsel.
Following the Clinton playbook, each side would have up to 24 hours to present its opening statement. Neither side has to use all of its time. The 24 hours would be split over three days for each side, as was the case during Clinton's trial. The trial is expected to take place six days a week, Monday through Saturday.
In the Clinton case, opening arguments were followed by a 16-hour question period, in which senators submitted questions for both sides to the chief justice. Then came a vote to dismiss the case, which failed, and then a vote on whether to hear from witnesses.
The Senate decided to depose three witnesses on video, and parts of their testimony were played during the trial.
Republicans would need 51 votes to dismiss the case, and there are 53 Republican senators, but there's little interest in the GOP in tossing out the case. Some moderate Republicans, including Mitt Romney of Utah and Susan Collins of Maine, have said they'd be open to calling witnesses. Democrats would need four Republicans to side with them for that to happen.
Schumer has named four people whom Democrats want to testify: acting White House chief of staff Mick Mulvaney; Robert Blair, senior adviser to Mulvaney; Michael Duffey, associate director for national security at the Office of Management and Budget; and former national security adviser John Bolton.
All four were asked to testify during the House impeachment inquiry last year, but they didn't at the direction of the White House.
Democrats' best bet might be Bolton, who has said he has new relevant information and would testify if subpoenaed by the Senate. Romney has said he'd "love to hear" what Bolton has to say.
Republicans haven't released a list of possible witnesses, but some have said they'd like to hear from former Vice President Joe Biden and his son, Hunter.
Trump had wanted Ukraine to investigate both of them because of the younger Biden's lucrative work on the board of the Ukrainian gas company Burisma. Some have also called for testimony from the whistleblower whose complaint alerted Congress to possible wrongdoing in Trump's call with Ukraine's president. Trump's personal lawyer Rudy Giuliani, meanwhile, is not part of the president's impeachment trial team and has said he would "love" to testify.
If witnesses do testify, they would likely be followed by closing statements and then deliberations, which would be held behind closed doors.