The two men were scheduled to leave for Orlando, where Mr. Trump is to deliver a speech at the International Association of Chiefs of Police annual conference in the early afternoon.

A Justice Department official confirmed that the Mr. Rosenstein planned to travel on Air Force One to accompany the president for his speech, but did not share an agenda for any meeting.

Presumably, Mr. Rosenstein and Mr. Trump will use their time on board to discuss the fact that the deputy attorney general had offered to secretly tape his conversations with Mr. Trump in the chaotic days after the president fired James B. Comey, the F.B.I. director, in the spring of 2017. At that time, Mr. Rosenstein also brought up the possibility of invoking the 25th amendment to remove Mr. Trump from the White House.