US President Donald Trump has been impeached by the House of Representatives days before leaving office, becoming the first American president to be impeached twice.

The previous three impeachments, those of presidents Andrew Johnson, Bill Clinton and Mr Trump, took months before a final vote, including investigations in the House and hearings.

This time it only took a week after Mr Trump encouraged a crowd of his supporters who attacked the US Capitol.

Democrats and 10 Republicans voted to impeach Mr Trump on one charge – incitement of insurrection.

Outgoing Senate leader Mitch McConnell has said the Senate will not begin a trial until next Tuesday, at the very earliest, which is the day before Democrat Joe Biden is sworn in as president.

It is unclear, for now, exactly how that trial will proceed and if any Senate Republicans will vote to convict Mr Trump.

Even though the trial will not happen until Mr Trump is already out of office, it could still have the effect of preventing him from running for president again.

Here is a look at the 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. Speaker Nancy Pelosi has not yet said when she will send them, but many Democrats in her caucus have urged her to do so immediately.

Ms Pelosi has already appointed nine impeachment managers to argue the case against Mr Trump in a Senate trial, a sign that she will send them sooner rather than later.

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 January 19, which could be Mr McConnell’s last day as Senate leader. Once Kamala Harris is sworn in as vice-president, 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.

Mr McConnell said he will not bring the Senate back on an emergency basis to start the trial, so the earliest it could begin would be Tuesday.

That means the trial is certain to take place after Mr Trump has already left office.

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

– All eyes on McConnell

Mr McConnell believes that Mr Trump committed impeachable offences and considers the Democrats’ impeachment drive an opportunity to reduce the divisive, chaotic president’s hold on the Republican party, a Republican strategist told The Associated Press on Wednesday.

And Mr McConnell told major donors over the weekend that he was through with Mr Trump, said the strategist.

His wife, former transportation secretary Elaine Chao, resigned from Mr Trump’s Cabinet soon after the riots.

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

– Senate politics

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

Still, some Republicans have told Mr Trump to resign and few are defending him.

Other Republicans have said that impeachment would be divisive. South Carolina senator 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 senator Mitt Romney was the only Republican to vote to convict Mr Trump in last year’s impeachment trial, after the House impeached him over his dealings with the president of Ukraine.

In the House, 10 Republicans joined Democrats in voting to impeach Mr Trump. Every single House Republican voted against Mr Trump’s first impeachment in 2019.

– Donald Trump’s future

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

Mr 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.”

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 Mr Trump’s dealings with the president of Ukraine, whom he urged to investigate Joe Biden, came after a lengthy investigation and testimony from many government officials.

While Democrats unanimously criticised the conduct and charged Mr 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.

Mr 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 chairman 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 Mr Trump “gravely endangered the security of the United States and its institutions of Government”.

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

Mr 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.