UPDATE - Trump picks budget director as new chief of staff

ADDS DETAILS THROUGHOUT

By Michael Hernandez

WASHINGTON (AA) - U.S. President Donald Trump selected Office of Management and Budget Director Mick Mulvaney to be his new acting chief of staff Friday.

"Mick has done an outstanding job while in the Administration," Trump said on Twitter. "I look forward to working with him in this new capacity as we continue to MAKE AMERICA GREAT AGAIN! John will be staying until the end of the year. He is a GREAT PATRIOT and I want to personally thank him for his service!"

Mulvaney will replace John Kelly, the decorated Marine Corps general who has reportedly found himself on the outs with the president in recent months.

Kelly is set to depart his post at the end of the year.

Mulvaney will be Trump's third chief of staff in under two years. Trump initially chose Republican political operative Reince Priebus to fill the role, but his tenure lasted only half a year.

While Trump dubbed Mulvaney his "acting" chief of staff, a senior administration official who addressed reporters at the White House later said there is no time limit on his tenure and as such "he’s the chief of staff."

Mulvaney will be replaced at the Office of Management and Budget by his deputy Russell Voight.