White House chief of staff John Kelly will quit his post at the end of the year – an exit being taken in Washington as further confirmation of chaos and rivalry in the White House.

Mr Kelly’s exit, confirmed by US President Donald Trump, marks the latest in a long list of advisers and cabinet members to come and go from the White House.

Speculation that Mr Kelly would resign has been rife in recent days, with media outlets citing a deterioration in the relationship between the president and his chief.

Former homeland security secretary Kelly was tasked with bringing order to the White House when he took over from Reince Priebus in July 2017.

In September, Washington Post veteran Bob Woodward reported that Mr Kelly had branded Mr Trump “an idiot”.

“It’s pointless to try to convince him of anything,” Mr Kelly was quoted in Woodward’s book on the Trump White House. “He’s gone off the rails. We’re in Crazytown.

“I don’t even know why any of us are here. This is the worst job I’ve ever had.”

Mr Kelly subsequently denied making those remarks and any discord between the president and his right-hand man was not evident in Mr Trump’s remarks when confirming the departure.

“John Kelly will be leaving – I don’t know if I can say ‘retiring’. But he’s a great guy,” Mr Trump told reporters, adding that Mr Kelly’s successor should be announced in the coming week.

US media outlets have pegged Vice-President Mike Pence’s 36-year-old chief of staff Nick Ayers as a likely candidate to take Mr Kelly’s place.

It is the second top-level personnel change Trump has made since the mid-term elections on November 6, after Attorney-General Jeff Sessions resigned last month at Mr Trump’s request.

-with AAP