WASHINGTON — In what will be one of the most crucial moments of his presidency, Donald Trump will find himself in an uncomfortable position, taking a back seat as someone else mounts his public defense.

Just days before opening arguments begin in his Senate impeachment trial, the president was still his own most visible and vocal defender.

"I JUST GOT IMPEACHED FOR MAKING A PERFECT PHONE CALL!" he tweeted Thursday. "They're trying to impeach the son of a bitch, can you believe that?" he complained Friday to Louisiana State University's college football champion team during their White House visit. Speaking at the American Farm Bureau Federation's annual convention in Austin, Texas, on Sunday, Trump lamented having been "impeached by these radical left lunatics."

But as the trial begins in earnest on Tuesday, Trump will be handing over the reins for one of the most crucial moments of his presidency to a team of his staunchest cable TV legal defenders, including former independent counsel Ken Starr, the famed defense lawyer Alan Dershowitz and former Florida Attorney General Pam Bondi.

After Democrats make their case, they will be given a block of time to lay out Trump's side in a historic scene that will be watched on television by millions. But Trump — who has boasted about not needing a defense team and has often said he views himself as his own best spokesman — will have no choice but to watch along with the rest of the public.

If the House hearings are any indication, the Senate trial should draw millions of viewers, giving Trump's team the opportunity to reach a broader audience than the one he and his allies can get to on Twitter or Fox News. About 13.8 million people watched the first public impeachment hearings in the House, which the White House refused to take part in, according to Nielsen.

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Even though Trump will have a hand in shaping what his defenders will say, the somber setting for oral arguments in the Senate won't provide the same freewheeling venue that the president is used to having in a Fox News interview, at a campaign rally or in a one-sided exchange with reporters as a helicopter roars in the background. And while all the members of his team have been solid defenders, none have the same bellicose style or flexibility with the truth as Trump.

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But while Trump won't have a visible role in the trial, he isn't expected to sit idly by, and his allies expect that the public relations battle will go well beyond what happens in the Senate chamber.

"The trial doesn't necessarily begin and end when Justice Roberts convenes and dismisses each day's session," said Jason Miller, Trump's former campaign communications adviser, who co-hosts a radio show on impeachment. "The overall public opinion battle will be raging 24 hours a day on the airwaves. That is important to keep in mind."

(Chief Justice John Roberts will preside over the trial.)

But if Trump weighs in, he also risks undermining his own defense. He has done so in the past, as when he acknowledged in a television interview that the firing of FBI Director James Comey was related to the Russia investigation.

Democrats are expected to make their case starting Tuesday, and if the model from President Bill Clinton's impeachment trial in 1999 is followed — and neither side pushes for delays — Trump's team up could come up next weekend.

Trump will have his own counterprogramming lined up for the day the trial is set to begin — even beyond his Twitter feed. He is expected to speak to business executives and world leaders Tuesday at the World Economic Forum in Davos, Switzerland, and to hold a series of meetings with his foreign counterparts while he is there, creating an opportunity to appear as a president hard at work above the fray of impeachment.

But Trump has often chosen to use his moments on the world stage to attack his domestic political rivals, and he'll have multiple opportunities in Davos. At the NATO meeting of world leaders in London early last month, while seated next to Canadian Prime Minister Justin Trudeau, Trump called House Intelligence Committee Chairman Adam Schiff a "maniac" and a "deranged human."

The trial could also stretch into his State of the Union address on Feb. 4, giving the president an uninterrupted prime-time speech before the body debating whether he should be removed from office.

The White House sent a six-page written answer to Congress on Saturday that attacked the process used by House Democrats during the impeachment inquiry and addressed the substance of the articles of impeachment, arguing that they don't include an impeachable offense. The White House plans to send a longer, more detailed brief by Monday.

While the issue of witnesses is yet to be decided, a person close to the legal team said White House is preparing for the possibility that both sides will call witnesses. The legal team is anticipating that White House counsel Pat Cipollone will open the defense, followed by one of Trump's attorneys, Jay Sekulow, who will detail more of the timeline, while Dershowitz and Starr will have "discrete functions" at certain times, the person said.

As the president's legal team gets ready to take center stage, Miller said the smart move for Trump would be to keep his own attacks going, as well.

"If President Trump were to stay quiet, it will be 100 percent negative information flow," Miller said. "It is up to him to get the information out. It should be a combination of pushing a positive message but don't be afraid to call out these House impeachment managers when need be."