Video clips from the roughly eight-hour deposition committee investigators conducted with former Trump White House counsel Pat Cipollone last Friday are expected to be played at the afternoon hearing, a source familiar with the matter tells ABC News.

Committee member Rep. Zoe Lofgren, D-Calif., said last week after Cipollone was subpoenaed by the committee that his testimony did not contradict those of previous witnesses when he met with investigators.

Asked if Americans could assume that Cipollone confirmed the testimony offered by Cassidy Hutchinson, a former top aide to Trump's then-chief of staff Mark Meadows, Lofgren told CNN, "Not contradicting is not the same as confirming."

While Hutchinson publicly testified last month that Cipollone stressed to her that Trump should not be taken to the Capitol after his rally, warning, "we're going to get charged with every crime imaginable" if he went, according to Hutchinson, it was not clear if the committee asked Cipollone in his deposition about the comment.

-ABC News' John Santucci and Katherine Faulders

Today's hearing will partly focus on a meeting in the Oval Office on Dec. 18, 2020. Sources confirmed the meeting to ABC News at the time.

The meeting was said to be so long that it ended up moving from the Oval Office to the White House residence quarters upstairs. In attendance were Trump allies Sidney Powell; former CEO Patrick Byrne; former national security adviser Michael Flynn; then-White House counsel Pat Cipollone; then-chief of staff Mark Meadows and Rudy Giuliani, who joined by phone.

Powell, Flynn and Byrne argued with White House officials over invoking rarely used presidential powers to declare a national emergency to seize voting machines – a plan that was ultimately rejected. Trump in the meeting also discussed naming Powell a special counsel overseeing an investigation of voter fraud, as first reported by the New York Times at the time.

ABC News Chief Washington Correspondent Jonathan Karl described the meeting in his book "Betrayal" as one "so bizarre, long, and out of control that it may go down in history as the strangest meeting Donald Trump, or any other president, ever had at the White House."

- ABC News' Katherine Faulders and Will Steakin

Reps. Stephanie Murphy, D-Fla., and Jamie Raskin, D-Md., will lead Tuesday's questioning, according to committee aides.

One focus of the hearing, aides said, will be the impact of a Twitter post sent by Trump in December 2020, which read: "Big protest in D.C. on January 6th. Be there, will be wild!"

"Today, we'll show how President Trump's tweet in the early hours of December 19th activated domestic extremist groups, and how some Members of Congress amplified that message, all leading to the attack on January 6th," Murphy said on Twitter.

An Ohio man who accused President Joe Biden, other Democrats, and the mainstream media of "treason" is set to testify in the public hearing this afternoon before the House committee investigating the Jan. 6 attack on the Capitol, according to a source familiar with the matter.

The hearing is expected to focus on the rise of radical extremism in the United States, and the source said one of the key witnesses will be Stephen Ayres of Warren, Ohio, who recently admitted to illegally entering the Capitol on Jan. 6, 2021.

A former spokesman for the Oath Keepers militia group, Jason Van Tatenhove, will also be testifying Tuesday, the source said.

-ABC News' Katherine Faulders and Mike Levine