WASHINGTON — The House committee investigating the Jan. 6 riot on Thursday requested cooperation from Ivanka Trump, as it revealed pieces of what it has learned about a scramble inside the White House that day to get President Donald J. Trump to denounce and call off the mob that was laying siege to the Capitol.
In a letter to Ms. Trump, the former president’s eldest daughter who served as one of his senior advisers, the committee said it had obtained evidence that multiple White House officials — including Ms. Trump, at least twice — had implored Mr. Trump to call off the violence, only to be rebuffed. But aides at the time were also worried about Mr. Trump issuing anything other than a scripted statement during the mayhem.
“Apparently, certain White House staff believed that a live, unscripted press appearance by the president in the midst of the Capitol Hill violence could have made the situation worse,” wrote Representative Bennie Thompson, Democrat of Mississippi and the panel’s chairman.
The summoning of Ms. Trump suggested that the committee was delving deeper into the question of what Mr. Trump was doing and saying while the attack unfolded, as it seeks to determine his intentions and state of mind during the assault. The letter also made clear that the panel has already uncovered substantial evidence about those critical hours inside the White House from key players who were present that day.
In the letter, Mr. Thompson wrote that investigators had received information from Keith Kellogg, a retired lieutenant general who was Vice President Mike Pence’s national security adviser, about Mr. Trump’s refusal to condemn the violence, despite White House officials urging him to do so.
Mr. Kellogg testified that Mr. Trump had rejected entreaties by him as well as Mark Meadows, his chief of staff, and Kayleigh McEnany, the White House press secretary. Mr. Kellogg then appealed to Ms. Trump to intervene.
“She went back in, because Ivanka can be pretty tenacious,” Mr. Kellogg testified.
He also told investigators that he had recommended “very strongly” against the president speaking on live television, because his “press conferences tend to get out of control.”
The committee also revealed that Mr. Kellogg testified that he and Ms. Trump witnessed a telephone call in the Oval Office on the morning of Jan. 6 in which Mr. Trump pressured Mr. Pence to go along with a plan to throw out electoral votes for Joseph R. Biden Jr. when Congress met to make its official count of the results, thus invalidating the 2020 election and allowing Mr. Trump to stay in office.
Mr. Kellogg told the committee that the president had accused Mr. Pence of not being “tough enough” to overturn the election.
Ms. Trump then turned to Mr. Kellogg and said, “Mike Pence is a good man,” Mr. Kellogg testified.
“The committee has information suggesting that President Trump’s White House counsel may have concluded that the actions President Trump directed Vice President Pence to take would violate the Constitution or would be otherwise illegal,” Mr. Thompson wrote to Ms. Trump. “Did you discuss those issues with any member of the White House Counsel’s Office?”
A spokesman for Ms. Trump said on Thursday that she had “just learned” that the committee “issued a public letter asking her to appear.”
“As the committee already knows, Ivanka did not speak at the Jan. 6 rally,” the spokesman said in a statement. “As she publicly stated that day at 3:15 p.m.: ‘Any security breach or disrespect to our law enforcement is unacceptable. The violence must stop immediately. Please be peaceful.’”
The request for Ms. Trump’s cooperation came the day after the panel won a major victory, when the Supreme Court refused a request from the former president to block the release of White House records concerning the Jan. 6 attack, effectively rejecting Mr. Trump’s claim of executive privilege and clearing the way for the House committee to start receiving the documents.
Within hours of that decision on Wednesday night, the National Archives began the process of turning over hundreds of pages of documents to the committee. A spokesman for the panel said on Thursday that it had received some of the documents and expected the rest to be delivered as quickly as the archives could produce them.
Mr. Thompson told reporters on Capitol Hill on Thursday that the committee would consider posting the documents publicly — including any fake electoral certificates for Mr. Trump that it obtains — after its investigators review the documents.
The committee’s letter to Ms. Trump also included evidence from court transcripts that showed how Mr. Trump’s public statements against Mr. Pence on Jan. 6 resonated with rioters.
“Once we found out Pence turned on us and that they had stolen the election, like, officially, the crowd went crazy,” one defendant said. “I mean, it became a mob. We crossed the gate.”
Another testified, “We heard the news on Pence,” adding, “So we stormed.”
The Justice Department has also been examining the ways in which Mr. Trump’s attacks on Mr. Pence influenced the mob. In recent plea negotiations in some Jan. 6 cases, prosecutors have asked defense lawyers whether their clients would admit in sworn statements that they stormed the Capitol believing that Mr. Trump wanted them to stop Mr. Pence from certifying the election.
Key Figures in the Jan. 6 Inquiry
In theory, such statements could help connect the violence at the Capitol directly to Mr. Trump’s demand that Mr. Pence help him stave off defeat.
At a court hearing in November for a Jan. 6 defendant, a federal prosecutor, James Pearce, suggested — without specifically naming Mr. Trump — that it would be a crime for someone to reach out to Mr. Pence and seek to steer him away from performing his constitutional responsibilities.
“Asking the vice president to do something the individual knows is wrongful,” Mr. Pearce said, would be “trying to get someone to violate a legal duty.”
The letter also revealed text messages from allies of Mr. Trump who believed he was going too far in his attempts to overturn the election. One message, from an unidentified member of the House Freedom Caucus who was aware of the president’s plans, warned Mr. Meadows that “if POTUS allows this to occur … we’re driving a stake in the heart of the federal republic.”
After Jan. 6, Mr. Meadows and Representative Jim Jordan, Republican of Ohio, who has refused to cooperate with the committee, received a text message from Sean Hannity, a Fox News host, laying out recommendations for how Mr. Trump should behave.
“He can’t mention the election again. Ever,” Mr. Hannity wrote on Jan. 10, according to the committee. “I did not have a good call with him today. And worse, I’m not sure what is left to do or say.”
Mr. Hannity also recommended to Ms. McEnany in text messages referred to by the committee that she and others who spoke to Mr. Trump impress upon him that there must be “no more stolen election talk,” and that “impeachment and 25th Amendment are real, and many people will quit.”
“Love that,” she responded. “Thank you. That is the playbook. I will help reinforce.”
“Key now. No more crazy people,” Mr. Hannity added, in an apparent effort to get White House staff members to keep Mr. Trump away from certain people who were encouraging his worst behavior.
“Yes 100 percent,” Ms. McEnany replied.
The letter to Ms. Trump was the committee’s latest step to try to obtain information from Mr. Trump’s inner circle, including his family, about the events that led up to the Capitol riot. The panel has also sought logs of phone calls and text messages between the former president’s son Eric Trump and Kimberly Guilfoyle, the girlfriend of another son, Donald Trump Jr., according to CNN.
Maggie Haberman, Alan Feuer and Emily Cochrane contributed reporting.