United States President, Donald John Trump and White House Chief of Staff John Francis Kelly
U.S. President Donald Trump gestures next to White House Chief of Staff John Kelly during a briefing with senior military leaders at the White House in Washington, U.S., October 5, 2017.Reuters file [Representational Image]

US President Donald Trump has announced that his Chief of Staff John Kelly will exit the White House by the end of the year.

Trump's announcement on Saturday came after it was reported on Friday that Kelly was expected to announce his departure in the coming days, reports CNN.

"John Kelly will be leaving at the end of the year," Trump told reporters before departing the White House for the Army-Navy game.

Trump noted Kelly had been with him for almost two years in his roles as Chief of Staff and Secretary of Homeland Security.

"I appreciate his service very much," the President said.

Kelly's status had become endangered in recent months as his relationship with the President deteriorated. He was not on speaking terms with Trump during his last days, officials told CNN, and their relationship was no longer seen as tenable.

Vice President Mike Pence's Chief of Staff, Nick Ayers, has been considered a top contender to replace Kelly for more than six months.

But Trump did not announce a replacement for Kelly on Saturday, saying only that he will in the coming days, and it's still unclear if Ayers will be offered the job.

Kelly, who did not travel with the President to Kansas City on Friday, was also reportedly interviewed by Special Counsel Robert Mueller's team in recent months.

The White House did not respond to request for comment about the discussions.

When Kelly first replaced Reince Priebus as Chief of Staff, he ruled with an iron fist, CNN said.

He curbed Oval Office access, blocked certain outsiders from being able to call the White House switchboard and executed authority over staffing.

White House officials believed Kelly was close to resigning after he got into a heated argument with National Security Advisor John Bolton in October.

Bolton had criticised Department of Homeland Security Secretary Kirstjen Nielsen during a discussion about the border, and Kelly stormed out of the West Wing after their profanity-laced argument.