John Kelly, White House chief of staff. Image Credit: Bloomberg

US President Donald Trump on Saturday announced his chief of staff John Kelly would be leaving the administration at the end of the year - the latest in a series of moves by the Republican leader to change his inner circle of aides.

Kelly, a retired Marine Corps general, was long rumored to be on the way out, amid reports that his relationship with the volatile Trump had deteriorated to such an extent they were no longer on speaking terms.

"John Kelly will be leaving at the end of the year," Trump said before heading to Philadelphia for the Army-Navy football game, adding that a replacement would be named "over the next day or two."

Kelly's replacement might be an interim chief of staff, until a permanent successor is found, the Republican president said.

"He's been with me almost two years now, between two positions," Trump told reporters. "I appreciate his service very much."

Although Kelly is credited with bringing some discipline to the Oval Office, his tenure was hardly smooth sailing.

Kelly was serving as secretary of the Department of Homeland Security when he was brought in on July 31, 2017 to replace Reince Priebus as White House chief of staff.

Kelly took over a White House plagued by political intrigue and under a cloud because of allegations of election collusion with Russia.

Trump, speaking with reporters on the White House lawn before departing for the Army-Navy football game in Philadelphia, said that he would announce a replacement for Kelly in the next day or two.

"John Kelly will be leaving - I don't know if I can say 'retiring,'" Trump said. "But he's a great guy. John Kelly will be leaving at the end of the year."

The leading candidate to replace Kelly is Nick Ayers, Vice President Mike Pence's 36-year-old chief of staff and a Republican political operative, who possesses the kind of savvy about campaigns that Trump has craved. Kelly, a career military officer before becoming Trump's first homeland security secretary, lacked such experience.

Kelly's coming departure leaves Trump with an ever-shrinking team of close advisers as he begins to navigate the new power structure on Capitol Hill that will be ushered in next month when Democrats assume control of the House.

Although the president had made a display of saying that Kelly, 68, would stay through the 2020 re-election effort, the chief of staff was blunt with several people in the White House that he planned to make it only through the midterms.

Presidents typically make changes in staffing after midterm elections. Kelly's resignation had long been rumored.