On Saturday, Senator Chuck Schumer of New York, the Democratic leader, urged Mr. Horowitz to open an investigation, saying that it was “unconscionable that a Trump Justice Department leader would conspire to subvert the people’s will.”
This is the second known investigation into the actions of top Justice Department officials during the final weeks of the Trump administration. Earlier this month, Mr. Horowitz opened an investigation into whether Trump administration officials improperly pressured Byung J. Pak, the U.S. attorney in Atlanta, who abruptly resigned after it became clear to Mr. Trump that he would not take actions to cast doubt on or undo the results of the election, according to a person briefed on the inquiry.
Separately, the Senate Judiciary Committee said this weekend that it has initiated its own oversight inquiry into officials including Mr. Clark.
Senator Richard J. Durbin of Illinois, the top Democrat on the committee, sent a letter to the Justice Department saying that he would investigate efforts by Mr. Trump and Mr. Clark to use the agency “to further Trump’s efforts to subvert the results of the 2020 presidential election.”
Mr. Durbin asked the acting attorney general, Monty Wilkinson, to preserve documents, emails and messages related to meetings between top Justice Department officials, the White House and Mr. Trump, as well as any communications related to Mr. Pak’s resignation.