Democrats are set to introduce an article of impeachment against outgoing President Donald Trump next week over the deadly Capitol unrest, as the drive is dividing Republicans in the Senate, the upper chamber responsible for holding a trial.

U.S. Congressman Ted Lieu from California, a Democratic member of the U.S. House Judiciary Committee, tweeted on Saturday that the article of impeachment, which has so far had 180 co-sponsors, will be brought forward during Monday's pro forma session in the lower chamber.

Lieu, Congressmen David Cicilline from Rhode Island, and Jamie Raskin from Maryland wrote the article of impeachment seeking to remove Trump for "incitement of insurrection" at the U.S. Capitol on Wednesday.

A bid crowd of Trump's supporters overwhelmed police and violently breached the Capitol on that day when Congress was certifying President-elect Joe Biden's victory in the 2020 White House race. The chaos and violence forced a lockdown on the Capitol grounds and left five people dead, including a police officer, and dozens of others injured.

Trump addressed a rally outside the White House shortly before the deadly violence unfolded on Capitol Hill, urging his supporters to march toward the landmark to encourage Republican lawmakers to contest the Electoral College results, as he had refused to acknowledge their legitimacy with unsubstantiated claims of voter fraud.

By Saturday, U.S. prosecutors have filed 17 cases in federal district court and 40 others in the District of Columbia Superior Court for a variety of offenses ranging from assaulting police officers to entering restricted areas of the U.S. Capitol, stealing federal property and threatening lawmakers.

House Speaker Nancy Pelosi, the top congressional Democrat, has publicly expressed support for initiating proceedings to impeach Trump for a second time in just over a year.

The House, led by Democrats, impeached Trump in 2019 after an inquiry triggered by a whistleblower complaint that raised concerns about the White House's interactions with Ukraine. The Republican-led Senate later acquitted the president, allowing him to continue holding office.

The U.S. Constitution provides that the House of Representatives "shall have the sole Power of Impeachment" and that "the Senate shall have the sole Power to try all Impeachments."

Through the impeachment process, the U.S. Congress charges and then tries an official of the federal government for "Treason, Bribery, or other high Crimes and Misdemeanors." The definition of "high Crimes and Misdemeanors" is not specified in the Constitution and has long been subject to debate.

Conviction can only happen in the U.S. Senate and requires at least two-thirds of its members, or 67 senators, to vote in favor of at least one article of impeachment after a trial. No sitting U.S. president has ever been removed from office by Congress through impeachment.

Senate Republicans have been divided over the impeachment push.

Senator Pat Toomey, a Pennsylvania Republican set to retire in 2022, told Fox News in an interview that he believes Trump has "committed impeachable offenses" by inciting violence at U.S. Capitol.

However, Toomey pointed out that he doesn't know whether it is "possible or practical" to move ahead with impeachment proceedings, since Trump only has 11 days left in office before Biden is sworn in on Jan. 20.

"I'm not sure it's desirable to attempt to force him out, what, a day or two or three prior to the day on which he's going to be finished anyway," he explained. "So I'm not clear that's the best path forward."

Senator Lindsey Graham, a South Carolina Republican and chairman of the Senate Judiciary Committee, tweeted on Friday that he thinks "any attempt to impeach President Trump would not only be unsuccessful in the Senate but would be a dangerous precedent for the future of the presidency."

"I'm convinced impeachment, under these circumstances, will further divide the country and erode the institution of the presidency itself," Graham wrote. "It will take both parties to heal the nation."

Outgoing Senate Majority Leader Mitch McConnell, a Kentucky Republican, has reportedly circulated to colleagues a memo outlining procedures for holding another trial for Trump in the upper chamber if the House impeaches him again.

The Senate is currently in recess until Jan. 19, a day before the end of Trump's presidency, and impeachment trial proceedings cannot begin before then unless all 100 senators consent to an early return, a scenario which is unlikely to happen.

Trump has announced he will not be attending Biden's inauguration, the first outgoing U.S. president to skip his successor's swearing-in in over 150 years.

Vice President Mike Pence reportedly will attend the event on Capitol Hill at the invitation of Biden.

The U.S. Congress on early Thursday morning affirmed the 2020 Electoral College votes, in which Biden won 306 versus 232 for Trump. It takes at least 270 electoral votes to win the White House. Biden also won the popular votes by 7 million and more than 4 percentage points.

Shortly after the congressional certification of Biden's victory, Trump acknowledged defeat and promised to ensure "a smooth, orderly and seamless transition of power."