US President Donald Trump has named Mick Mulvaney, the director of the office of management and budget, as acting White House chief of staff.
Mr Mulvaney, 51, replaces General John Kelly, who is leaving by the end of the year.
In a tweet, Mr Trump described Mr Kelly as a "great patriot", who had served the country with distinction.
But earlier this year, General Kelly was forced to deny he had called Mr Trump an "idiot".
This came after the quote was included in a book about Mr Trump by the veteran investigative journalist Bob Woodward.