WASHINGTON (AP) — Donald Trump's historic second impeachment trial will launch this week with a debate and a vote on whether it's even constitutional to prosecute the former president over the deadly Capitol siege now that he's no longer in office.

The details are coming together in a draft agreement between Senate Majority Leader Chuck Schumer and Senate Republican Leader Mitch McConnell, according to a person granted anonymity to discuss the ongoing talks.

There will likely be no witnesses called during the trial, and the former president has declined a request to testify. The proceedings will break Saturday for the Jewish Sabbath, at the request of Trump's defense team.

The trial will push into a Sunday session.

Trump's second impeachment trial is opening this week with a sense of urgency — by Democrats who want to hold the former president accountable for the violent U.S. Capitol siege and Republicans who want it over as fast as possible.

Scheduled to begin Tuesday, just over a month since the deadly riot, the proceedings are expected to diverge from the lengthy, complicated trial that resulted in Trump's acquittal a year ago on charges that he privately pressured Ukraine to dig up dirt on a Democratic rival, Joe Biden, now the president. This time, Trump's Jan. 6 rally cry to “fight like hell” and the storming of the Capitol played out for the world to see. While Trump very well could be acquitted again, the trial could be over in half the time.

Under the terms of the trial being negotiated, it would launch first with a debate over its constitutionality, a key argument of the former president's defense.

Sen. Rand Paul, R-Ky., forced a vote on the issue last month, and senators will again be confronted with a debate and vote.

Opening arguments would begin Wednesday at noon, with up to 16 hours per side for presentations.

Details of the proceedings are still being negotiated by the Senate leaders, and whether or not witnesses are called is up to the House managers

Trump is the first president to be twice impeached, and the only one to face trial after leaving the White House. The Democratic-led House approved a sole charge, “incitement of insurrection,” acting swiftly one week after the riot, the most violent attack on Congress in more than 200 years. Five people died including a woman shot by police inside the building and a police officer who died of injuries the next day.

There will be no trial proceedings on Friday evening or into Saturday, at the request of the defense team because of the Jewish Sabbath. The trial would reconvene Sunday afternoon, which is Valentine’s Day.

So far, it appears there will be few witnesses called, as the prosecutors and defense attorneys speak directly to senators who have been sworn to deliver “impartial justice” as jurors. Most are also witnesses to the siege, having fled for safety that day as the rioters broke into the Capitol and temporarily halted the electoral count certifying Biden's victory.

Defense attorneys for Trump declined a request for him to testify. Holed up at his Mar-a-Lago club in Palm Beach, Florida, the former president has been silenced on social media by Twitter without public comments since leaving the White House.

Instead, House managers prosecuting the case are expected to rely on the trove of videos from the siege, along with Trump's incendiary rhetoric refusing to concede the election, to make their case. His new defense team has said it plans to counter with its own cache of videos of Democratic politicians making fiery speeches.

“We have the unusual circumstance where on the very first day of the trial, when those managers walk on the floor of the Senate, there will already be over 100 witnesses present,” said Rep. Adam Schiff, D-Calif., who led Trump's first impeachment. "Whether you need additional witnesses will be a strategic call.”

Democrats argue it’s not only about winning conviction, but holding the former president accountable for his actions, even though he’s out of office. For Republicans, the trial will test their political loyalty to Trump and his enduring grip on the GOP.

Initially repulsed by the graphic images of the siege, Republican senators including Senate Republican leader Mitch McConnell denounced the violence and pointed a finger of blame at Trump. But in recent weeks GOP senators have rallied around Trump arguing his comments do not make him responsible for the violence. They question the legitimacy of even conducting a trial of someone no longer in office.

On Sunday, Republican Sen. Roger Wicker of Mississippi described Trump's impeachment trial as a “meaningless messaging partisan exercise." Republican Sen. Rand Paul of Kentucky called the proceedings a farce with “zero chance of conviction" and described Trump’s language and rally words as “figurative” speech.

Senators were sworn in as jurors late last month, shortly after Biden was inaugurated, but the trial proceedings were delayed as Democrats focused on confirming the new president's initial Cabinet picks and Republicans sought to put as much distance as possible from the bloody riot.

At the time, Paul forced a vote to set aside the trial as unconstitutional because Trump is no longer in office, drawing 44 other Republicans to his argument.

A prominent conservative lawyer, Charles Cooper, rejects that view, writing in a Wall Street Journal opinion piece Sunday that the Constitution permits the Senate to try an ex-official, a significant counterpoint to that of Republican senators who have looked toward acquittal by advancing constitutional claims.

Republican Sen. Lindsey Graham of South Carolina, one of Trump’s ardent defenders, said he believes Trump’s actions were wrong and “he’s going to have a place in history for all of this,” but insisted it’s not the Senate’s job to judge.

“It’s not a question of how the trial ends, it’s a question of when it ends,” Graham said. “Republicans are going to view this as an unconstitutional exercise, and the only question is, will they call witnesses, how long does the trial take? But the outcome is really not in doubt.”

But 45 votes in favor of Paul's measure suggested the near impossibility of reaching a conviction in a Senate where Democrats hold 50 seats but a two-thirds vote — or 67 senators — would be needed to convict Trump. Only five Republican senators joined with Democrats to reject Paul’s motion: Mitt Romney of Utah, Ben Sasse of Nebraska, Susan Collins of Maine, Lisa Murkowski of Alaska and Pat Toomey of Pennsylvania.

Schiff was on NBC's “Meet the Press, Wicker spoke on ABC's “This Week,” Paul was on “Fox News Sunday” and Graham was on CBS' “Face the Nation.”

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Associated Press writers Eric Tucker and Mary Clare Jalonick contributed to this report.