By Jeremy Herb, Manu Raju, Lauren Fox and Phil Mattingly, CNN

(CNN) -- House Democrats formally introduced their resolution to impeach President Donald Trump on Monday, charging him with "incitement of insurrection" for his role in last week's riots at the US Capitol.

The impeachment resolution that the House is poised to vote on later this week is the Democrats' first step toward making Trump the first president in history to be impeached twice.

Democrats also tried to move a resolution Monday urging Vice President Mike Pence to invoke the 25th Amendment to remove Trump from power, but House Republicans blocked the request.

The single impeachment article, which was introduced when the House gaveled into a brief pro-forma session Monday, points to Trump's repeated false claims that he won the election and his speech to the crowd on January 6 before pro-Trump rioters breached the Capitol. It also cited Trump's call with the Georgia Republican secretary of state where the President urged him to "find" enough votes for Trump to win the state.

"In all this, President Trump gravely endangered the security of the United States and its institutions of Government," the resolution says. "He threatened the integrity of the democratic system, interfered with the peaceful transition of power, and imperiled a coequal branch of Government. He thereby betrayed his trust as President, to the manifest injury of the people of the United States."

The resolution, which was introduced by Democrats David Cicilline of Rhode Island, Jamie Raskin of Maryland and Ted Lieu of California, also cited the Constitution's 14th Amendment, noting that it "prohibits any person who has 'engaged in insurrection or rebellion against' the United States" from holding office.

House Speaker Nancy Pelosi told House Democrats on Sunday evening that the House would proceed with bringing an impeachment resolution to the floor this week unless Pence moves to invoke the 25th Amendment with a majority of the Cabinet to remove Trump from power.

Pelosi's letter was the first time she explicitly said that the House would take up impeachment on the floor this week, though it was clear that House Democrats have rapidly coalesced around an impeachment resolution in the days following the riots at the Capitol where five people died, including a US Capitol Police officer.

The level of unity in the Democratic caucus is being driven by the visceral reaction to what happened on January 6, when lawmakers had to be evacuated from the House and Senate chambers with rioters banging on the doors outside as the insurrectionists tried to stop the counting of votes to affirm President-elect Joe Biden would become President on January 20.

Still, as Democrats race toward impeachment, the President-elect's advisers have expressed concerns about an impeachment trial in the Senate hampering the opening days of Biden's presidency, and Democrats are still debating how to handle the timing of the impeachment articles and a possible Senate trial.

House Majority Leader Steny Hoyer said Monday that he expects the vote to impeach Trump to occur on Wednesday, and he wants the articles sent to the Senate without delay. Because Senate Majority Leader Mitch McConnell has said he won't bring back the Senate from recess before January 19, that would push the trial into the beginning of the Biden administration.

Cicilline told CNN Monday that he supports sending impeachment articles to the Senate right away, too. He said "we have the numbers" already to impeach Trump, and he predicted some Republicans would vote for it, too, unlike the House's December 2019 votes to impeach Trump.

"I expect that we'll have Republican support," Cicilline said. "I think it's urgent that the president be removed immediately."

Democrats on Monday sought to take up a resolution from Raskin urging Pence and the Cabinet to invoke the 25th Amendment. Hoyer asked for unanimous consent to bring up the resolution, but West Virginia GOP Rep. Alex Mooney objected to the request. Pelosi has said the Democrats will move to bring the resolution for a floor vote on Tuesday.

Pelosi said she was calling on Pence to respond within 24 hours of the House passing Raskin's 25th Amendment resolution. If that does not happen, Democrats will bring their impeachment resolution to the floor.

Pelosi said in an interview on CBS' "60 Minutes" that she liked the idea of invoking the 25th Amendment "because it gets rid of him," but explained, "one of the motivations people have for advocating for impeachment" is to prevent Trump from holding office again.

"There's strong support in the Congress for impeaching the President a second time," she said.

House Democrats are holding a caucus-wide call on Monday to discuss their path forward.

House Republicans have urged Democrats not to move forward with impeachment, arguing that such a move would be divisive in the face of Biden's calls for unity. House Minority Leader Kevin McCarthy is also holding a conference call with the GOP conference Monday, according to a source familiar.

Still, there's been little to slow momentum toward impeachment since Wednesday. Two Senate Republicans, Lisa Murkowski of Alaska and Pat Toomey of Pennsylvania, have called on Trump to resign in the wake of the insurrection at the Capitol.

Biden has said he is leaving the response to Congress, but House Democrats' impeachment push threatens to complicate his agenda when he takes office on January 20, and his advisers have been consulting with the House.

A Senate impeachment trial beginning on January 20 -- Biden's inauguration -- would grind the chamber to a halt, unable to confirm nominees or enact legislation until the trial was finished.

One option being considered is waiting until later to send the articles to the Senate: House Democratic Whip James Clyburn said on CNN's "State of the Union" Sunday the House might wait until after Biden's first 100 days in office before sending the impeachment articles to the Senate to begin the trial. But Hoyer's comments Monday seemed to suggest that was an unlikely move, since it would cut against Democrats' argument that removing Trump is an urgent priority.

This story has been updated with additional developments Monday.