The Mueller Report:
When Priebus and Bannon learned that the President was holding onto Sessions’s resignation letter, they became concerned that it could be used to influence the Department of Justice. Priebus told Sessions it was not good for the President to have the letter because it would function as a kind of “shock collar” that the President could use any time he wanted; Priebus said the president had “DOJ by the throat.” Priebus and Bannon told Sessions they would attempt to get the letter back from the President with a notation that he was not accepting Sessions’s resignation.
On May 19, 2017, the President left for a trip to the Middle East. Hicks recalled that on the President’s flight from Saudi Arabia to Tel Aviv, the President pulled Sessions’s resignation letter from his pocket, showed it to a group of senior advisors, and asked them what he should do about it. During the trip, Priebus asked about the resignation letter so he could return it to Sessions, but the President told him that the letter was back at the White House, somewhere in the residence. It was not until May 30, three days after the President returned from the trop, that the President returned the letter to Sessions with a notation saying, “Not accepted.”