Peter Navarro, who as a White House adviser to President Donald J. Trump worked to keep Mr. Trump in office after his defeat in the 2020 election, disclosed on Monday that he has been summoned to testify on Thursday to a federal grand jury and to provide prosecutors with any records he has related to the attack on the Capitol last year, including “any communications” with Mr. Trump.
The subpoena to Mr. Navarro — which he said the F.B.I. served at his house last week — seeks his testimony about materials related to the buildup to the Jan. 6 attack on the Capitol, and signals that the Justice Department investigation may be progressing to include activities of people in the White House.
Mr. Navarro revealed the existence of the subpoena in a draft of a lawsuit he said he is preparing to file against the House committee investigating the Jan. 6 attack, Speaker Nancy Pelosi and Matthew M. Graves, the U.S. attorney for the District of Columbia.
Mr. Navarro, who plans to represent himself in the suit, is hoping to persuade a federal judge to block the subpoena, which he calls the “fruit of the poisonous tree.”
The Justice Department and the U.S. Attorney’s Office declined to comment.
The grand jury’s subpoena, Mr. Navarro said, builds on a separate subpoena issued to him in February by the committee. That subpoena sought documents and testimony about an effort to overturn the election nicknamed the “Green Bay Sweep,” and a Jan. 2, 2021, call that Mr. Navarro participated in with Mr. Trump and his lawyers in which they attempted to persuade hundreds of state lawmakers to join the effort.
Mr. Navarro has refused to cooperate with the committee. He was found in contempt of Congress, and the House referred the contempt case to the Justice Department for possible criminal prosecution. In his draft lawsuit, he called the committee’s subpoena “illegal and unenforceable.”
Mr. Navarro said the grand jury subpoena was directly related to the contempt of Congress referral. Asked if he planned to comply and appear on Thursday to testify, Mr. Navarro responded, “T.B.D.”
The subpoena is the latest sign the Justice Department’s investigation into the attack has moved beyond the pro-Trump rioters who stormed the Capitol. Federal prosectors have charged more than 800 people in connection with the attack.
The subpoena sent last week to Mr. Navarro is the first known to have been issued in connection to the department’s Jan. 6 investigations to someone who worked in the Trump White House. But it follows others issued to people connected to various strands of the sprawling investigation of the Capitol attack and its prelude.
In April, Ali Alexander, a prominent “Stop the Steal” organizer, revealed that he had been served with his own grand jury subpoena, asking for records about people who organized, spoke at or provided security for pro-Trump rallies in Washington after the election, including Mr. Trump’s incendiary event near the White House on Jan. 6.
Mr. Alexander’s subpoena also sought records about members of the executive or legislative branches who may have helped to plan or execute the rallies, or who tried to “obstruct, influence, impede or delay” the certification of the 2020 presidential election.
Last week, word emerged that the same grand jury, sitting in Washington, had more recently issued a different set of subpoenas requesting information about the role that a group of lawyers close to Mr. Trump may have had played in a plan create alternate slates of pro-Trump electors in key swing states that were won by Joseph R. Biden Jr.
The lawyers named in the subpoena included Mr. Trump’s personal attorney, Rudolph W. Giuliani; Jenna Ellis, who worked with Mr. Giuliani; John Eastman, one of the former president’s chief legal advisers during the postelection period; and Kenneth Chesebro, who wrote a pair of memos laying out the details of the plan.
Those subpoenas also requested information about any members of the Trump campaign who may been involved with the alternate elector scheme and about several Republican officials in Georgia who took part in it, including David Shafer, the chairman of the Georgia Republican Party.
Mr. Navarro’s subpoena, by his own account, was issued by a different grand jury.
In the draft of the suit he said he intends to file, he argues that only Mr. Trump can authorize him to testify. He asks a judge to instruct Mr. Graves, the U.S. attorney in Washington, to negotiate his appearance with Mr. Trump. Mr. Navarro cites Mr. Trump’s invocation of executive privilege over materials related to the attack on the Capitol.
“The executive privilege invoked by President Trump is not mine or Joe Biden’s to waive,” Mr. Navarro writes. “Rather, as with the committee, the U.S. attorney has constitutional and due process obligations to negotiate my appearance.”
An effort by Mr. Trump to block release of White House materials related to the Jan. 6 attack on the grounds of executive privilege was rejected by a federal appeals court in January, and the Supreme Court denied Mr. Trump’s request for a stay of the decision.
Mr. Navarro, who helped coordinate the Trump administration’s pandemic response through his role overseeing the Defense Production Act, has insisted that the violence at the Capitol on Jan. 6 was not part of the plans he backed, which he said included having Vice President Mike Pence reject electors for Mr. Biden when Congress met in a joint session to formally count them.
In a book, Mr. Navarro wrote that the idea for the “Green Bay Sweep” was for Mr. Pence to be the “quarterback” of the plan and “put certification of the election on ice for at least another several weeks while Congress and the various state legislatures involved investigate all of the fraud and election irregularities.”
Mr. Navarro also wrote a 36-page report claiming election fraud as part of what he called an “Immaculate Deception.” In an interview with The New York Times, he said he relied on “thousands of affidavits” from Mr. Giuliani, and Bernard B. Kerik, the former New York police commissioner, to help produce the report, which claimed there “may well have been a coordinated strategy to effectively stack the election deck against the Trump-Pence ticket.”
There is no evidence of widespread fraud in the 2020 election, and the Jan. 6 committee described the claims in Mr. Navarro’s report as having been “discredited in public reporting, by state officials and courts.”
Mr. Navarro said that he made sure Republican members of Congress received a copy of his report and that more than 100 members of Congress had signed on to the plans. (Ultimately, 147 Republican members of Congress objected to certifying at least one state for Mr. Biden.)
An aide to Mr. Navarro was also in contact with a group of Trump allies who were pushing for the former president to order the seizure of voting machines.