Rep. Liz Cheney, R-Wyo., gaveled in the committee around 8 p.m. as Chairman Bennie Thompson participates virtually after testing positive for COVID-19.

Cheney, the committee's vice chair, will preside over the hearing. Thompson said she will be responsible for maintaining order and swearing in witnesses.

Thompson also gave a preview of what's in store tonight as the committee analyzes Trump's response to the attack as it unfolded on Jan. 6, 2021.

"For 187 minutes, this man of destructive energy could not be moved," Thompson said of Trump. "He could not be moved to rise from his dining room table, and walk the few steps down to the press room."

Thompson said the committee's work won't stop here, stating it will reconvene in September.

Rep. Bennie Thompson, D-Miss., will chair the committee remotely after testing positive for COVID-19. He announced his diagnosis on Monday.

"Gratefully, I am fully vaccinated and boosted," he said at the time. "I am continuing to follow CDC guidelines and will be isolating for the next several days."

During Thursday's hearing, the House select committee is expected to show outtakes from former President Donald Trump's recorded message delivered on Jan. 7, in which he condemned the attack on the Capitol and pledged a "seamless transition of power."

But sources familiar with their contents tell ABC News that Trump had to be pressured to condemn the attack, taking about an hour to record this message: "The demonstrators who infiltrated the Capitol have defiled the seat of American democracy. To those who engaged in the acts of violence and destruction, you do not represent our country."

Sources say Trump argued with aides as the statement was being written and wanted to call the attackers patriots. -- ABC News Chief Washington Correspondent Jonathan Karl

Just ahead of Thursday's hearing, committee member Rep. Pete Aguilar, D-Calif., said Americans can expect to learn "exactly what was happening" on Jan. 6 from when former President Donald Trump left his rally to his address in the Rose Garden three hours later.

"Where was the president at? Who was talking to him? What was he saying?" Aguilar told anchor Linsey Davis on ABC News Live Prime. "Those are the types of details that we want to get to, because while the Capitol was being overrun and law enforcement officers were providing the last line of defense to save democracy, I think it's important that the American public knows what was going on at the White House."

Aguilar said the hearing will also address Trump's statements on social media the day after the attack.

"The statements and addresses that he made on Jan. 6 and Jan. 7 are both important to his state of mind at the time and what he was willing to say and more importantly, what he wasn't willing to say," he said.

Aguilar said the committee continues to receive investigative material that may come out.

"To the extent that we need to share that with the American public, we plan to do that," he said. "Our responsibility is to find the truth here. And that's what we plan to do."