Democrats in the US Congress will try to remove President Donald Trump from office this week, either by pressuring Vice President Mike Pence or in a historic second impeachment attempt, after Trump's supporters stormed the Capitol building.

Here's what to expect in the coming days:

Monday: Introducing resolution asking Pence to act

On Monday, House Democrats will try to pass a resolution asking Pence to invoke the 25th Amendment of the US Constitution, which allows the vice president and the Cabinet to remove a president deemed incapable of doing his job.

The resolution, drafted by Democratic Representative Jamie Raskin, accuses Trump of pressuring election officials to overturn his defeat and encouraging his supporters to march on the Capitol.

The House is due to convene in a "pro forma" session at 11am ET, when few members are expected to be present.

Republicans are likely to block the attempt to pass the resolution without a full, recorded vote.

Democratic House Speaker Nancy Pelosi and Republican House Minority Leader Kevin McCarthy have scheduled private afternoon conference calls with their members.

Tuesday: A vote on the 25th Amendment request

If Republicans block immediate action, the House will hold a formal, recorded vote on Tuesday, according to Pelosi. The measure is expected to pass the House, where Democrats hold a 222-211 majority.

The vote would apply pressure to Pence, but it would not force him to act. It gives him 24 hours to respond.

Pence rebuffed Trump's entreaties to somehow prevent Congress from certifying Democratic President-elect's Joe Biden victory, and the two men are not currently speaking to each other, sources say.

Nevertheless, it is unclear whether Pence would be willing to invoke the 25th Amendment, or whether he would get support from enough Cabinet members to go through with it.

After that: Impeachment

Assuming Pence does not act, the House would next bring impeachment legislation up for a vote, Pelosi said.

Democratic Representatives Ted Lieu, David Cicilline and Jamie Raskin have introduced an article of impeachment calling for Trump's removal from office due to "incitement of insurrection." The measure has the support of more than 200 Democrats.

The House Rules committee would set the parameters for debate and vote on the House floor, which could take place as soon as Wednesday or Thursday.

The impeachment motion would likely pass the House, given its strong support among Democrats who control the chamber. That would make Trump the only U.S. president to be impeached twice.

On to the Senate

Impeachment is akin to an indictment - it leads to a trial in the US Senate, which earlier this year acquitted Trump in his first impeachment.

A two-thirds vote would be needed to convict Trump of the impeachment charge and remove him from office.

That means all 50 Democrats and at least 17 of the chamber's 50 Republicans would have to vote to convict him. As of Sunday, only two Senate Republicans have publicly said that Trump should not serve out his term.

Timing is also an issue as Trump's term ends 20 January, when Biden is sworn in.

The Senate is required to consider impeachment charges as soon as they get them from the House, but it is not due to return until 19 January.

That means the Senate would be consumed with impeachment during Biden's first weeks in office, rather than voting on his Cabinet nominations and other policy priorities, such as responding to the Covid-19 pandemic.

The House could avoid this scenario by simply waiting to send the impeachment charge to the Senate for 100 days, as Democratic Representative James Clyburn suggested on CNN on Sunday.

That would allow Congress to focus on Biden's agenda. By the time the Senate turned to the impeachment charge, Trump would be long out of the White House. But if they voted to convict, he would be prevented from holding public office in the future.

- Reuters