Mick Mulvaney: Budget director to replace John Kelly as Trump's chief of staff

Donald Trump has named budget director Mick Mulvaney as his new chief of staff, replacing General John Kelly, who leaves the post in January.

Mr Trump said in a tweet on Friday that Mr Mulvaney "has done an outstanding job" in his administration and would take over as "acting chief of staff" next year.

It was not clear what "acting" meant for how long he planned to stay in the role.

Earlier, former New Jersey Governor Chris Christie became the latest high-profile candidate to pull out of the running for one of the most powerful jobs in the White House.

In a statement, Mr Christie said: "Now is not the right time for me or my family to undertake this serious assignment. As a result, I have asked him to no longer keep me in any of his considerations for this post."

In the week since Mr Kelly announced he was leaving, speculation has swirled over his successor.

The president's first choice was Nick Ayers, Vice President Mike Pence's chief of staff, who bowed out after being unable to come to an agreement on how long he would serve in the role.

By Friday, the president's son-in-law Jared Kushner was considered to be a serious possibility.

Mr Kushner, a White House adviser with responsibility for Middle East policy, was believed to be one of five candidates on a shortlist Mr Trump said on Thursday he was reviewing.

Appeals from both in and outside the White House had been made to Mr Trump promoting Mr Kushner's credentials, Reuters said, quoting two sources.

Also reportedly on the list was US trade representative Robert Lighthizer, who has been at the heart of Mr Trump's trade policy, overhauling foreign trade deals by using tariffs to try to open markets.

To his critics in Washington, the prolonged search illustrates that the chaos of the Trump administration is making it harder for the White House to function.

The White House chief of staff - in effect the president's gatekeeper - is considered to be one of the plum Washington posts, as it involves carrying out the president's priorities and making sure he has the information to make decisions.

But it is widely reported Mr Trump does not enjoy reading briefs, makes up policy on the hoof and has little time for detailed analysis, making the chief of staff's role much harder than usual.

As well as the difficulty of managing Mr Trump, Mr Mulvaney faces a daunting in-tray when he takes up the role next month, with the looming threat of increased scrutiny from a Democrat-controlled House of Representatives and the continued fallout from the Russia investigation.

Mr Kelly lasted nearly a year and a half, having succeeded Mr Trump's first chief of staff, Reince Priebus, who left after six months.

Both men found themselves dealing with regular crises in the often chaotic and factional Trump White House, where personal alliances can count for more than policy clarity and political nous.

Journalist and TV presenter Piers Morgan had offered to take on the role, and, in a bizarre twist, so had former baseball star Jose Canseco.