Vice-chair Liz Cheney focused her opening statement Thursday on teasing a draft letter that Trump and former DOJ official Jeffrey Clark wanted the department to send to Georgia officials citing already disproven allegations of fraud.

"As you will see, this letter claims that the U.S. Department of Justice's investigations have 'identified significant concerns hat may have impacted the outcome of the election in multiple states, including the state of Georgia,'" Cheney said. "In fact, Donald Trump knew this was a lie. The Department of Justice had already informed the president of the United States repeatedly that its investigations had found no fraud sufficient to overturn the results of the 2020 election."

ABC News obtained and published the draft letter in full last year. Read it here.

Cheney also said the public today will see video testimony by three members of Trump's White House staff identifying certain members of Congress who contacted the White House after Jan. 6 to "seek presidential pardons for their conduct."

Three former top officials in the Justice Department -- former acting attorney general Jeffrey Rosen, former deputy acting attorney general Richard Donoghue and former top DOJ lawyer Steven Engel -- sat before lawmakers Thursday as Committee Chair Bennie Thompson, D-Miss., convened the fifth public hearing this month.

"Today, we'll tell the story of how the pressure campaign also targeted the federal agency charged with enforcement of our laws, the Department of Justice," Thompson said, going to call it "a brazen attempt to use the Justice Department to advance the president's professional and personal agenda."

All three witnesses are expected to detail how they resisted Trump and his allies' repeated entreaties to enlist the Justice Department in his failed bid to overturn his election loss.

Rep. Adam Kinzinger will lead questioning in today’s hearing, committee aides confirmed to reporters. Kinzinger is one of the two Republicans on the nine-member committee.

"The threat to our democracy is real. And today, we'll see just how close we came to losing it all," Kinzinger tweeted ahead of the hearing. "Tune in as we uncover President Trump’s pressure campaign on [the Justice Department] in his desperate attempt to subvert the will of the people to stay in power."

British documentary filmmaker Alex Holder sat for a deposition with the committee earlier Thursday after a subpoena commanded him to turn over documentary footage -- never-seen publicly -- filmed for a series on Trump's final months in office.

"I have no further comment at this time other than to say that our conversation today was thorough and I appreciated the opportunity to share more context about my project," Holder said in a statement to ABC News.

Holder was "given unparalleled access and exclusive interviews with President Trump, Ivanka, Eric, and Don Jr., Jared Kushner as well as Vice President Pence; in the White House, Mar-A-Lago, behind-the-scenes on the campaign trail, and before and after the events of January 6th," according to a statement from his spokesperson.

He received a subpoena last Thursday from the committee to turn over footage shot for his documentary series and submitted the materials requested earlier this week.

-ABC News Ali Dukakis

Former acting deputy attorney general Richard Donoghue said he tried to convey to Jeffrey Clark that a draft letter he circulated seeking to ask Georgia's governor and other top state officials to convene the state legislature into a special session to investigate claims of voter fraud -- which didn't exist -- could launch the country into a "constitutional crisis."

"I had to read both emails and the attached letter twice to make sure I really understood what he was proposing -- because it was so extreme to me, I had a hard time getting my head around it initially," he recalled, adding he and former acting attorney general Jeffrey Rosen had "visceral reactions to it."

"I thought it was very important to get a prompt response rejecting this out of hand. In my response, I explained a number of reasons that this is not the department's rule to suggest or dictate [to] state legislatures," he said.

"More importantly, this was not based on fact. This was actually contrary to the facts as developed by department investigations over the last several weeks and months," he added. "For the department to insert itself into the political process this way, I think, would have had great consequences for the country. It may very well have spiraled into a constitutional crisis -- and I want to make sure that he understood the gravity of the situation because he did not seem to really appreciate it."