John Kelly is expected to depart his role as White House Chief of Staff by the end of the year, President Donald Trump said on Saturday, ending a tenure marked by tensions with his boss and confrontations with other key administration figures.

Kelly's departure follows several months of controversy and turmoil, and comes at a time when the president's agenda is imperiled by a midterm election in which Democrats recaptured the House of Representatives. The chief of staff vacancy is just the latest changing of the guard at the administration's highest levels, which includes the U.S. Attorney General, United Nations ambassador and Joint Chiefs of Staff.

The president announced the news on the front lawn on the White House, following days of swirling speculation around the retired Marine Corps general's exit for months amid disagreements with Trump. Nevertheless, in his brief remarks to reporters, Trump called Kelly "a great guy" and that he appreciated his service.

"We'll be announcing who will be taking John's place" over the next day or two, Trump said, en route to the annual Army-Navy football game. Vice President Mike Pence's chief of staff, Nick Ayers, is reportedly among the candidates who could succeed Kelly, but Reuters reported that the parties were still thrashing out the details.

NBC News and The New York Times reported on Saturday that Ayers was only willing to commit to an interim term through the spring, as his family is expected return to Georgia, citing people familiar with the discussions. Yet the president, eager to tamp down on the storyline of his White House in chaos, wants Ayers to stay on full time.