Jan. 6 Panel Hints at Fresh Revelations as Hearing Is Delayed

WASHINGTON — A day after the Jan. 6 attack on the Capitol, Eric Herschmann, a White House lawyer, received an unexpected call from the conservative lawyer John Eastman, who had been working with President Donald J. Trump to try to overturn the results of the 2020 election.

To Mr. Herschmann’s surprise — even after the deadly riot — Mr. Eastman was still pushing to fight the election results, an effort that resulted in mayhem and violence.

Mr. Herschmann cut him off.

“I’m going to give you the best free legal advice you’re ever getting in your life,” he recalled telling Mr. Eastman before recommending he find a criminal defense lawyer, adding, “You’re going to need it.”

The House committee investigating the Jan. 6 attack on the Capitol released video of Mr. Herschmann’s testimony as it previewed a hearing Thursday in which the panel plans to delve into the pressure campaign Mr. Trump and Mr. Eastman waged against Vice President Mike Pence as they tried to persuade him to throw out legitimate electoral votes for Joseph R. Biden Jr. to keep Mr. Trump in power.

“President Trump had no factual basis for what he was doing, and he had been told it was illegal,” Representative Liz Cheney, Republican of Wyoming and the vice chairwoman of the committee, said in a video previewing the hearing.

Thursday’s hearing is expected to include potentially important revelations about the steps Mr. Trump and his allies took to try to compel his vice president to overturn the election.

J. Michael Luttig, a conservative former judge who advised the vice president, is scheduled to testify. Judge Luttig advised Mr. Pence that Mr. Trump’s idea that the vice president could unilaterally decide to invalidate election results was unconstitutional and that he should not go along with the plan.

Also scheduled to appear is Greg Jacob, Mr. Pence’s top White House lawyer, who has provided the committee with crucial evidence about the role played by Mr. Eastman, who wrote a memo that members of both parties have described as a blueprint for a coup.

Mr. Eastman advised Mr. Trump that Mr. Pence could throw out electoral votes from states he had lost, though he conceded during a conversation with Mr. Jacob that his arguments carried no legal weight and would fail before the Supreme Court.

As the mob attacked the Capitol on Jan. 6 — some of them chanting “Hang Mike Pence!” — Mr. Jacob sent an email to Mr. Eastman blaming him for the violence.

“Thanks to your bullshit, we are now under siege,” Mr. Jacob wrote at 12:14 p.m.

“It was gravely, gravely irresponsible for you to entice the president with an academic theory that had no legal viability,” Mr. Jacob wrote in a subsequent email to Mr. Eastman.

The committee could also hear testimony about Mr. Trump’s state of mind during the violence.

Ms. Cheney said last week that the panel had received testimony that when Mr. Trump learned of the mob’s threats to hang Mr. Pence, he said, “Maybe our supporters have the right idea,” and added that Mr. Pence “deserves it.”

The committee could also hear testimony that a day before the mob violence, Mr. Pence’s chief of staff, Marc Short, grew so concerned about Mr. Trump’s actions that he presented a warning to a Secret Service agent: The president was going to publicly turn against the vice president, and there could be a security risk to Mr. Pence because of it.

The committee on Tuesday postponed a hearing that was scheduled for Wednesday to lay out its findings about Mr. Trump’s attempt to use the Justice Department to overturn the 2020 election.

“It’s just technical issues,” said Representative Zoe Lofgren, Democrat of California and a member of the committee. She said that for staff aides who were compiling a series of videos to be showcased at the session, “it was overwhelming, so we’re trying to give them a little room.”

Maggie Haberman contributed reporting.