Mulvaney currently serves as White House budget director and will succeed John Kelly.

President Trump on Friday appointed budget director Mick Mulvaney acting chief of staff, choosing a trusted adviser and former Republican congressman to help shepherd the White House through looming battles with Congress over spending and oversight. In a tweet, Mr. Trump said Mr. Mulvaney would replace outgoing chief of staff John Kelly, who is set to depart the administration at the end of the year. Mr. Trump called Mr. Kelly a “great patriot” who had “served our country with distinction.”

Mr. Trump praised Mr. Mulvaney as having done an “outstanding job” in the administration. The president met with Mr. Mulvaney earlier Friday, a White House official said. A person familiar with the matter said it was possible Mr. Mulvaney could keep the position permanently. Asked why Mr. Trump had named him as an acting director, a White House official said: “Because that’s what the president wants.” Mr. Trump’s announcement puts at least a temporary halt to a search in which three leading candidates for the job pulled out of the running this past week.

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