In historic move, House Jan. 6 committee votes to subpoena Trump

Committee aides, during a background call with reporters on Wednesday, wouldn't shed any light on whether and when they would call Trump or former Vice President Mike Pence to formally testify before the panel before their investigation is wrapped.

Pence this summer said he would "consider" testifying if invited by the committee but expressed constitutional concerns about such a scenario, citing his "unique role" as the then-vice president.

Vice chair Liz Cheney, R-Wyo., told ABC News' Jonathan Karl in August that she hopes Pence will appear before the committee but declined to weigh in on whether they would ask Trump to testify.

"I don't want to get in front of committee deliberations about that," Cheney said. "I do think it's very important, as I said in the first hearing or the second hearing, you know, his interactions with our committee will be under oath."

--ABC News' Katherine Faulders

Lawmakers will focus on Trump's "state of mind" leading up to, during and after the insurrection during Thursday's session, committee aides told reporters.

"What you're going to see is a synthesis of some evidence we've already presented with that new, never-before-seen information to, let's say, illustrate Donald Trump's centrality from the time prior to the election," an aide said.

While there won't be any live witnesses in the hearing room, the panel's expected to air new documentary evidence and video footage depicting efforts to respond as the violence broke out on Jan. 6, 2021.

The hearing is expected to kick off at 1 p.m.