WASHINGTON (NewsNation Now) — House Democrats on Thursday asked Donald Trump to testify under oath for his Senate impeachment trial, challenging the former president to respond to their charge that he incited a violent mob to storm the Capitol. In a response, a Trump adviser said Trump won’t testify.

The request in a letter from House impeachment managers does not require Trump to appear, though the Senate could later force a subpoena, it does warn that any refusal to testify could be used at trial to support arguments for a conviction.

Even if Trump never testifies, the request nonetheless makes clear Democrats’ determination to present an aggressive case against him even though he has left the White House.

Hours after the letter was released, Trump adviser Jason Miller said that “the president will not testify in an unconstitutional proceeding.” Separately, Trump’s lawyers dismissed the request as a “public relations stunt.”

The Senate impeachment trial starts Feb. 9. Trump is charged with inciting an insurrection on Jan. 6, when a mob of his supporters broke into the Capitol to interrupt the electoral vote count. Democrats have said a trial is necessary to provide a final measure of accountability for the attack. If he is convicted, the Senate could hold a second vote to disqualify him from seeking office again.

Five people, including a Capitol Police officer, died during the riot. 

In a letter to Trump and his attorneys, Democratic Rep. Jamie Raskin, one of the impeachment managers, asked that Trump explain why he and his lawyers have disputed key factual allegations at the center of their charge. He asked that Trump provide testimony about his conduct “either before or during the Senate impeachment trial,” and under cross-examination, as early as Monday, Feb. 8, and not later than Thursday, Feb. 11.

The request from Raskin cites the words of Trump’s own attorneys, who in a legal brief earlier this week not only denied that Trump had incited the riot, but also asserted that he had “performed admirably in his role as president, at all times doing what he thought was in the best interests of the American people.”

With that argument, Raskin said, Trump had questioned critical facts in the case “notwithstanding the clear and overwhelming evidence of your constitutional offense.” He said Trump should be able to testify now that he is no longer president.

Trump attorneys Bruce Castor and David Schoen responded hours later that the letter proves that Democrats “cannot prove your allegations” and that an impeachment trial is too serious “to try to play these games.”

If Trump refuses to appear, Raskin said the managers will use his refusal against him in the trial — a similar argument put forth by House Democrats in last year’s impeachment trial, when many Trump officials ignored subpoenas. Trump was eventually acquitted of the Democratic charges that he abused his presidential powers by pressuring the Ukrainian government to investigate now-President Joe Biden.

The impeachment managers do not have the authority to subpoena witnesses now since the House has already voted to impeach him. The Senate could vote to subpoena Trump, or any other witnesses, on a simple majority vote during the trial.

On Thursday, senators in both parties made it clear they would be reluctant to do so.

Shortly after Raskin’s letter was made public, Sen. Chris Coons, D-Del., said it would be a “terrible idea” for Trump to testify. Sen. Richard Blumenthal, D-Conn., said Trump’s statements before and after the attack on the Capitol “are the most powerful evidence. His own words incriminate him. They show his guilty intent.”

South Carolina Sen. Lindsey Graham, one of Trump’s closest GOP allies, said he thinks the letter is a “political ploy” and notes that Democrats didn’t invite or subpoena Trump to testify before the House voted to impeach him on Jan. 13.

Asked if he thinks Trump will testify, Graham said it would be a “bad idea.”

“I don’t think that would be in anybody’s interest,” he said.

Read Rep. Jamie Raskin’s full letter:

Read Bruce Castor’s full letter:

The Associated Press and Reuters contributed to this report.