House Republican Leader Kevin McCarthy said in a letter to Republican colleagues that he does not support the Democrats' effort to impeach Trump. 

"Personally, I continue to believe that an impeachment at this time would have the opposite effect of bringing our country together when we need to get America back on a path towards unity and civility," McCarthy wrote in his letter that he sent Monday, obtained by ABC News. 

Instead, he is pushing for four other alternatives to impeachment, including a resolution of censure under the rules of the House, a bipartisan commission to investigate the circumstances surrounding the attack, reforming the Electoral Count Act of 1887 and legislation to promote voter confidence in future federal elections

-ABC News' Mariam Khan

Acting Homeland Security Secretary Chad Wolf is resigning from the Trump administration effective at 11:59 p.m. Monday, according to an internal message sent to staff at the department, citing "recent events."

"I am saddened to take this step, as it was my intention to serve the Department until the end of this Administration. Unfortunately, this action is warranted by recent events, including the ongoing and meritless court rulings regarding the validity of my authority as Acting Secretary. These events and concerns increasingly serve to divert attention and resources away from the important work of the Department in this critical time of a transition of power," he said in an email to colleagues.

-ABC News' Luke Barr

The House of Representatives is expected to return at 9 a.m. Tuesday to debate and pass a bill via a roll call vote demanding Vice President Mike Pence mobilize the Cabinet to remove Trump from office through the 25th Amendment. The vote is expected around 7:30 p.m., according to House Majority Leader Steny Hoyer’s office.

Democrats will give Pence "24 hours after passage" to respond, said House Speaker Nancy Pelosi in a statement earlier Monday, otherwise they will likely move forward with an impeachment vote on Wednesday, setting up Trump to be the first president in U.S. history impeached twice.

“The President’s threat to America is urgent, and so too will be our action,” Pelosi said in the statement.

As of right now, no Republicans have signed on to the legislation that calls on Pence to invoke the 25th Amendment, which is a likely indicator as to what happens with a potential vote on impeachment.

But sources tell ABC News that it’s possible some Republicans may vote to impeach Trump.

The single article of impeachment charging Trump with “incitement of insurrection” also cites Trump's call with the Georgia Republican secretary of state where he urged him to "find" enough votes for Trump to win the state and, separately, cites 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.

-ABC News' Mariam Khan

Acting Homeland Security Secretary Chad Wolf said Monday that in light of the "the evolving security landscape leading up to the inauguration and at the recommendation of Secret Service Director James Murray," he is going have the Secret Service designate the inauguration as a "National Special Security Event" beginning on Wednesday, Jan. 13, as opposed to Jan. 19 as previously slated. 

District of Columbia Mayor Muriel Bowser called on the Department of Homeland Security in an earlier press conference for the delegation to begin on Monday.

She also asked the Department of Interior to cancel all public gathering permits in the District through Jan. 24 and urged Americans not to travel to the nation's capital for the inauguration.

Starting this week and running through at least Inauguration Day, armed protests are being planned at all 50 state capitols and at the U.S. Capitol, according to an internal FBI bulletin obtained by ABC News.

-ABC News' Aaron Katersky and Luke Barr