WASHINGTON – The Senate impeachment trial of President Donald Trump resumes Tuesday, with senators mapping out how to conduct the proceeding before hearing opening arguments from House Democrats who will prosecute the case and White House lawyers defending the president.

Here are some questions and answers about what to expect from only the third trial in history of a sitting president:

How will the trial work?

The Constitution grants the Senate the sole power to hold an impeachment trial. The only three requirements are that senators swear an oath, that a two-thirds majority is required to remove an official and that the Supreme Court chief justice presides over the trial of a president. All other aspects of the trial must be hammered out.

The trial opened Thursday with the swearing in of Chief Justice John Roberts. He then administered the oath to senators. The House managers and White House lawyers filed written arguments over the weekend.

When the trial resumes Tuesday at 1 p.m., senators will debate how to conduct the trial, under what is called an organizing resolution. The resolution will detail logistics such as when the trial will start each day and how long each phase will last.

Senate Majority Leader Mitch McConnell, R-Ky., proposed allocating 24 hours to each side to present their case over two session days for each side. Then senators would have 16 hours to pose written questions through Roberts to both sides. Under his proposal, four hours of debate over whether to subpoena witnesses or documents would come after the opening arguments and questions.

But Senate Minority Leader Chuck Schumer, D-N.Y., said he would offer amendments. He said the proposal wouldn't automatically allow House Democrats to admit their evidence into the record and would have arguments continue into "the wee hours of the night" to hide information from the American people.

“Under this resolution, Sen. McConnell is saying he doesn’t want to hear any of the existing evidence, and he doesn’t want to hear any new evidence," Schumer said.

A 51-vote majority of the Senate will determine rules for the trial, in a chamber with 53 Republicans and 47 Democrats.

Will there be witnesses at the trial?

One of the most contentious aspects of the rules will be whether to call witnesses. Democrats want to call at least four witnesses, including former national security adviser John Bolton. But some Republicans said they would be unnecessary. If witnesses are allowed, Republicans have suggested calling the whistleblower who sparked the impeachment inquiry and Hunter Biden, the son of former Vice President Joe Biden.

Senate Majority Leader Mitch McConnell, R-Ky., said he has the votes to delay a decision on witnesses until after hearing opening arguments from House managers and White House lawyers, and after senators submit written questions to both sides.

"When you get to that issue, I can't imagine that only the witnesses that our Democratic colleagues would want to call would be called," McConnell said.

Senate Minority Leader Chuck Schumer, D-N.Y., has urged subpoenas for four witnesses and three batches of documents.

“As soon as Sen. McConnell offers this resolution, I will be offering amendments to address the many flaws in this deeply unfair proposal and to subpoena the witnesses and documents we have requested," Schumer said.

But even GOP senators open to hearing witnesses have said they would wait to decide until after opening statements and written questions, as McConnell suggested.

"While I need to hear the case argued and the questions answered, I tend to believe having additional information would be helpful," said Sen. Susan Collins, R-Maine, who supported calling witnesses in the 1999 trial for former President Bill Clinton. "Prior to hearing the statement of the case and the senators asking questions, I will not support any attempts by either side to subpoena documents or witnesses."

Who will argue the case?

Seven House Democrats, who are called managers, will present the case accusing Trump of abusing the power of his office by pressuring Ukraine to investigate his rival, former Vice President Joe Biden, while withholding $391 million in military aid. Trump is also accused of obstruction of Congress, for what Democrats say was his effort to stonewall the investigation.

The managers are: Intelligence Chairman Adam Schiff, D-Calif.; Judiciary Chairman Jerry Nadler, D-N.Y.; and Reps. Hakeem Jeffries, D-N.Y.; Zoe Lofgren, D-Calif.; Val Demings, D-Fla.; Jason Crow, D-Colo.; and Sylvia Garcia, D-Texas. All are lawyers except Demings, who was Orlando's police chief.

Trump's lead defenders will be White House counsel Pat Cipollone and private attorney Jay Sekulow. Other lawyers who have defended the president on television and will contribute to his team are Alan Dershowitz, a noted Harvard law professor; Kenneth Starr, the independent counsel who investigated Clinton; and Robert Ray, who replaced Starr as independent counsel during the last year of the Clinton presidency.

Is the trial public?

The trial is public, but could be closed at times as senators debate rules or the verdict. Votes on rules and the verdict will be public.

Security is tightened for the trial, restricting access in the Senate wing of the Capitol. Staffers and reporters need special credentials. But the balconies overlooking the chamber will remain open for the public and reporters to observe the proceedings.

The trial will be televised, but by cameras operated by the government. C-Span, the cable channel that carries gavel-to-gavel coverage of the Senate and House, has asked for more access for private cameras, as happens during the State of the Union speech or joint sessions of Congress.

The Senate could go into closed session at times. Under Senate Rule XXI, any senator can make a motion to go into closed session and, if seconded, the Senate moves into closed session by clearing the galleries and closing the doors. Lawmakers and staffers are prohibited from revealing what is discussed in closed sessions.

The Senate routinely met in secret in past centuries while debating treaties or nominations. Senators have met secretly dozens of times in the last century for debate over national security issues and for impeachment, according to a Congressional Research Service report. Six secret sessions were held during the 1999 trial of Clinton, the report said.

Senate Minority Leader Chuck Schumer, D-N.Y., said there might be closed sessions, but that his preference could be to keep most of the trial open.

"Might there be an occasional moment where we think we might come together in closed session? Yes," Schumer said. "But the strong presumption is to be open, and I want to see as much of it open as possible."

How long will the trial last?

There is no deadline to finish the trial. Early estimates were that hearing arguments from House managers and White House lawyers, with written questions from senators, could take two weeks. If senators agree to call witnesses, senators have estimated it could take three or four weeks longer.

The 1999 trial for Clinton took about six weeks, with pauses for filing written arguments and for deposing witnesses.

What about the State of the Union?

President Donald Trump has accepted an invitation from the House to give his State of the Union speech to a joint session of Congress on Feb. 4. The timing was compelling even without the Senate trial, coming a day after the Iowa presidential caucuses that will start to determine the Democratic nominee to challenge Trump in the fall.

House Speaker Nancy Pelosi, D-Calif., said Trump has several options. She said the president could could deliver his speech, he could submit a printed statement, "which was for a long time a tradition," or he could ask to postpone until after the trial is resolved.

"That's up to the president," Pelosi said.

Sen. Roy Blunt, R-Mo., expects Trump to deliver the speech even if the trial is still going.

“As I recall, President Clinton gave his State of the Union in the middle of that process, and I would expect no reason to believe that same thing wouldn’t happen," Blunt said.

But Sen. Lindsey Graham, R-S.C., told Fox News on Sunday that Trump preferred to have the trial over before the speech.

"His mood is to go to the State of the Union with this behind him and talk about what he wants to do for the next, rest of 2020 and what he wants to do for the next four years," Graham said. "He is very much comfortable with the idea that this is going to turn out well for him."