WASHINGTON -- Now that the House has impeached U.S. President Donald Trump for the second time, Speaker Nancy Pelosi must figure out the best strategy for arguing the case before the Senate.

Senate rules say the trial must start soon after the chamber receives the article of impeachment, which charges "incitement of insurrection" after an angry mob of Trump's supporters invaded the Capitol last week. But Pelosi has not said when the House will deliver it.

If the House sends it to the Senate early next week, or before then, a trial could begin at 1 p.m. on Inauguration Day, Jan. 20. President-elect Joe Biden will be sworn in at noon.

What is certain for now is that the impeachment trial will be held after Trump has already left office. Biden has said the Senate should be able to split its time confirming his nominees and passing legislative priorities while also holding hearing the impeachment case.

But it's still unclear exactly how the trial will proceed and if any Senate Republicans will vote to convict Trump.

A look at next steps:

SENDING TO THE SENATE

Once the House votes to impeach, the speaker of the House can send the article or articles over to the Senate immediately -- or she can wait a while. Many Democrats in Pelosi's caucus have urged her to do so immediately.

The speaker met this week with the nine impeachment managers she appointed to argue the case and is also consulting the Senate, according to Colorado Rep. Diana DeGette, who is one of the managers. She says it "hasn't been settled yet" when the House will send them over.

Another of Pelosi's managers, Pennsylvania Rep. Madeleine Dean, said Thursday that "what we did in the House, in bringing forth a single article of impeachment with the urgency that we did, I think should indicate to you that we feel an urgency in our caucus to move forward."

Once the articles are sent over -- that is usually done with an official walk from the House to the Senate -- then the majority leader of the Senate must start the process of having a trial.

THE SENATE SCHEDULE

The Senate is not scheduled to be in session until Jan. 19, which could be Senate Re,publican leader Mitch McConnell's last day as Senate leader. Once Vice-President Kamala Harris is sworn in, making her the president of the Senate, and Georgia's two Democratic senators are also sworn in, Senate Democratic leader Chuck Schumer will take charge and determine how the trial will proceed.

McConnell said Wednesday he would not bring the Senate back on an emergency basis to start the trial, meaning it won't conclude until after Trump has left office.

In the past two impeachment trials -- that of Bill Clinton in 1999 and Trump last year -- the trial started the day after the articles were received. If the Senate follows that precedent and Pelosi sends the articles to the Senate by Jan. 19, then the trial would begin on Jan. 20.

McConnell noted that the three previous Senate trials lasted "83 days, 37 days, and 21 days respectively."

ALL EYES ON MCCONNELL

McConnell is considering voting to convict after the president's impeachment, having told associates he is done with Trump. His wife, former Transportation Secretary Elaine Chao, resigned from Trump's Cabinet soon after the riots.

But despite sending signals, McConnell has been characteristically quiet in public. In a note to colleagues Wednesday released by his office, McConnell said he had "not made a final decision on how I will vote."

SENATE POLITICS

If McConnell voted to convict, other Republicans would surely follow. But no GOP senators have said how they will vote, and two-thirds of the Senate is needed.

Still, some Republicans have told Trump to resign, including Pennsylvania Sen. Pat Toomey and Alaska Sen. Lisa Murkowski, and few are defending him.

Republican Sen. Ben Sasse of Nebraska has said he would take a look at what the House approves, but stopped short of committing to support it.

Other Republicans have said that impeachment would be divisive. South Carolina Sen. Lindsey Graham, long a key ally of the president, has been critical of his behaviour in inciting the riots but said impeachment "will do far more harm than good."

Utah Sen. Mitt Romney was the only Republican to vote to convict Trump in last year's impeachment trial, after the House impeached Trump over his dealings with the president of Ukraine.

In the House, 10 Republicans joined Democrats in voting to impeach Trump, including Wyoming Rep. Liz Cheney, the third-ranking Republican. Every single House Republican voted against Trump's first impeachment in 2019.

TRUMP'S FUTURE

If the Senate were to convict, lawmakers could then take a separate vote on whether to disqualify Trump from holding future office.

Schumer said Wednesday: "Make no mistake, there will be an impeachment trial in the United States Senate; there will be a vote on convicting the president for high crimes and misdemeanours; and if the president is convicted, there will be a vote on barring him from running again."

In the case of federal judges who were impeached and removed from office, the Senate has taken a second vote after conviction to determine whether to bar the person from ever holding federal office again.

Only a majority of senators would be needed to ban him from future office, unlike the two-thirds needed to convict.

DIFFERENT CHARGES, DIFFERENT IMPEACHMENT

This impeachment trial is likely to differ from the last one in many ways.

The House charges in 2019 on Trump's dealings with the president of Ukraine, whom he urged to investigate Biden, came after a lengthy investigation and testimony from multiple government officials. While Democrats unanimously criticized the conduct and charged Trump with abuse of power, the charges wove together a complicated web of evidence.

This time, Democrats felt there was little need for an investigation -- the invasion of the Capitol played out on live television, and most members of Congress were in the building as it happened.

"The senators who are going to be sitting there are not are not just observers, they actually were victims of this same crime like the rest of us were," said DeGette.

Trump's speech beforehand, in which he told his supporters to "fight like hell" against the election results, was also televised as Congress prepared to officially count the votes.

House Intelligence Committee Chair Adam Schiff, who led the last House impeachment team, said the insurrection at the Capitol was an "impeachable offence committed in broad daylight, in which the whole country was a witness."

He said the lightning-fast impeachment "was required by the exigency of the circumstances, and also made possible by the very nature of the crime."

THE ARTICLE

The four-page article of impeachment says that Trump "gravely endangered the security of the United States and its institutions of Government."

It was introduced by Democratic Reps. David Cicilline of Rhode Island, Ted Lieu of California and Jamie Raskin of Maryland, all of whom have been tapped to serve as impeachment managers in the Senate trial.

The article says Trump's behaviour is consistent with his prior efforts to "subvert and obstruct" the results of the election and references his recent call with the Georgia secretary of state, in which he said he wanted him to find him more votes after losing the state to Biden.

Trump has falsely claimed there was widespread fraud in the election, and the baseless claims have been repeatedly echoed by congressional Republicans and the insurgents who descended on the Capitol.

As the protesters broke in, both chambers were debating GOP challenges to the electoral vote count in Arizona as part of the process for certifying Biden's election win.

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Associated Press writers Lisa Mascaro, Alan Fram and Jessica Gresko contributed to this report from Washington.