First, he claimed that a dispute years ago over fees at Trump National Golf Club in Sterling, Va., had prompted Mr. Mueller, the F.B.I. director at the time, to resign his membership. The president also said Mr. Mueller could not be impartial because he had most recently worked for the law firm that previously represented the president’s son-in-law, Jared Kushner. Finally, the president said, Mr. Mueller had been interviewed to return as the F.B.I. director the day before he was appointed special counsel in May.