Jan. 6 hearing told Trump knew plan to pressure Pence was illegal, went ahead anyway

Pence himself will not appear before the committee, but his adviser Greg Jacob -- who was with the former vice president the day of the Capitol insurrection -- is slated to testify. Jacobs, who is an attorney, pushed back against legal theories that Pence could single-handedly stop Joe Biden from becoming president.

Former federal judge Michael Luttig will also testify in front of lawmakers. Luttig previously told ABC News that if Pence had attempted to keep Trump in power, he would’ve "plunged the country into a constitutional crisis of the highest order."

In addition to the live witnesses, the committee is expected to include pre-recorded video testimony from Marc Short, Pence's former chief of staff, and others who have been deposed behind closed doors.

Rep. Pete Aguilar, D-Calif., is going to be leading this third hearing, which he said will “lay out new evidence about the pressure campaign against Vice President Pence asking him to reject the votes of millions of people.”

Former U.S. Attorney John Wood will also be questioning the witnesses on Thursday, according to committee aides. Wood was federal prosecutor during the George W. Bush administration and is now a senior investigative counsel for the House committee.

Aguilar told reporters earlier this week that through these public hearings, the committee is making the point that “Trump was at the center of a coordinated strategy to overturn the results of a free and fair election.”

The House select committee investigating the attack on the Capitol will convene its third public hearing of the month at 1 p.m. with members set to focus on how former President Donald Trump pressured then-Vice President Mike Pence with "relentless effort" to intervene to help overturn the 2020 election.

"President Trump had no factual basis for what he was doing and he had been told it was illegal," Vice Chair Liz Cheney said in a video teasing Thursday's hearing. "Despite this, President Trump plotted with a lawyer named John Eastman and others to overturn the outcome of the election on Jan. 6."

A key component of evidence is never-before-seen photos of Pence and his family taken by an official White House photographer on Jan. 6 itself. In one -- obtained by ABC News' Jonathan Karl ahead of the hearing -- second lady Karen Pence is seen hurriedly closing the curtains of the vice president's ceremonial office at the Capitol, apparently fearful the mob outside could see where they were.

Last week, at the prime-time kickoff to this round of hearings, Cheney teased testimony to come around Trump's awareness of rioters' "hang Mike Pence" chants. Quoting from witness testimony, Cheney said Trump suggested as the attack was underway: "Maybe our supporters have the right idea. Mike Pence deserves it."