As December wore on, Mr. Clark mentioned to Mr. Rosen and Mr. Donoghue that he spent a lot of time reading on the internet — a comment that alarmed them because they inferred that he believed the unfounded conspiracy theory that Mr. Trump had won the election. Mr. Clark also told them that he wanted the department to hold a news conference announcing that it was investigating serious accusations of election fraud. Mr. Rosen and Mr. Donoghue rejected the proposal…

On New Year’s Eve, the trio met to discuss Mr. Clark’s refusal to hew to the department’s conclusion that the election results were valid. Mr. Donoghue flatly told Mr. Clark that what he was doing was wrong. The next day, Mr. Clark told Mr. Rosen — who had mentored him while they worked together at the law firm Kirkland & Ellis — that he was going to discuss his strategy with the president early the next week, just before Congress was set to certify Mr. Biden’s electoral victory.

Unbeknown to the acting attorney general, Mr. Clark’s timeline moved up. He met with Mr. Trump over the weekend, then informed Mr. Rosen midday on Sunday that the president intended to replace him with Mr. Clark, who could then try to stop Congress from certifying the Electoral College results. He said that Mr. Rosen could stay on as his deputy attorney general, leaving Mr. Rosen speechless.