President Donald Trump revealed Friday that he has appointed budget director Mick Mulvaney to be the acting White House chief of staff.

Mulvaney will temporarily replace John Kelly, who is set to leave by the end of the year. Trump announced the news in a pair of tweets in which he thanked Kelly for his service and called him a “great patriot.”

Very few people appear to have been enticed by serving as Trump’s chief of staff. Earlier Friday, former New Jersey Gov. Chris Christie took himself out of the running for the job, saying this was not the right moment for him personally to serve in the role.

“It’s an honor to have the President consider me as he looks to choose a new White House chief-of-staff,” Christie wrote in a statement shared by Maggie Haberman of The New York Times on Friday. “However, I’ve told the President that now is not the right time for me or my family to undertake this serious assignment. As a result, I have asked not to be considered for this post.”

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Among the other candidates Trump has reportedly considered for the chief of staff position are North Carolina Republican Rep. Mark Meadows — the outgoing House Freedom Caucus chairman —  Treasury Secretary Steve Mnuchin and U.S. Trade Representative Robert Lighthizer, although all have reportedly said they prefer to continue serving in their current jobs. Vice President Mike Pences outgoing chief of staff Nick Ayers also rejected the offer for the role earlier this week.

The Daily Beast revealed this week that Trump’s son-in-law and senior adviser Jared Kushner was  interested in being White House chief of staff early in the administration’s tenure.