Under Justice Department rules, Mr. Trump would seemingly have to order Deputy Attorney General Rod J. Rosenstein to rescind department regulations protecting a special counsel from being fired for no good reason, and then to fire Mr. Mueller. If Mr. Rosenstein refused, Mr. Trump could fire him, too — a series of events that would recall the “Saturday Night Massacre” during Watergate, when President Richard M. Nixon sought to dismiss a special prosecutor, Archibald Cox.
White House officials referred questions to Mr. Trump’s personal lawyer, Marc E. Kasowitz, as they have recently on all matters relating to the Russia investigation. A spokesman for Mr. Kasowitz declined to comment.