The committees asked the Justice Department to allow former officials to testify after they opened investigations this year into the Trump White House’s efforts to undermine Mr. Biden’s victory, a pressure campaign that occurred in the weeks before Mr. Trump’s supporters attacked the Capitol as Congress met to certify the electoral results.
The Justice Department and the White House Counsel’s Office generally deny such requests because they believe deliberative conversations between administration officials should be protected from public scrutiny.
But they ultimately decided to allow the interviews to proceed, saying in letters to the potential witnesses that the scope of the investigation concerned “extraordinary events,” including whether Mr. Trump tried to improperly use the Justice Department to advance his “personal political interests,” and thus constituted “exceptional circumstances.”
In his letter, which was reported earlier by Politico, Mr. Collins also said Mr. Trump continued to believe that the information sought by the committees “is and should be protected from disclosure by executive privilege.”
Mr. Collins said that no president had the power to unilaterally waive that privilege, and that the Biden administration had “not sought or considered” Mr. Trump’s views in deciding not to invoke it.
“Such consideration is the minimum that should be required before a president waives the executive privilege protecting the communications of a predecessor,” Mr. Collins wrote.
The committees have also received a slew of emails, handwritten notes and other documents from the department that show how Mr. Trump, Mark Meadows, his former chief of staff, and others pushed the department to look into voter fraud allegations not supported by evidence, to ask the Supreme Court to vacate the election results and to publicly cast doubt on the outcome.
Congress has asked six former officials to testify in addition to Mr. Rosen and Mr. Donoghue. That list includes Patrick Hovakimian, Mr. Rosen’s former chief of staff; Byung J. Pak, the former U.S. attorney in Atlanta; Bobby L. Christine, the former U.S. attorney in Savannah, Ga.; and Jeffrey Clark, the former acting head of the Civil Division.
