President Donald Trump announced Friday that Stephen Miller will become his White House chief of staff on Monday, replacing Susie Wiles in the most significant staff shake-up of his second term — three days after Republicans suffered sweeping losses in the midterm elections.

“I am pleased to announce that Mr. Stephen Miller, the current Deputy Chief of Staff of the Trump Administration, and one of my most trusted advisors, will become the Chief of Staff starting Monday, November 9, 2026,” Trump wrote in a post on Truth Social.

Trump said Wiles, who has served as chief of staff since the start of his second term, “will be moving over to the Trump Political Operation.” “Susie Wiles, who has done an outstanding job, will be moving over to the Trump Political Operation. I want to thank her for her service as Chief of Staff — She has done a great job!” he wrote.

Miller has been one of Trump’s closest advisers since his first presidential campaign, and as deputy chief of staff for policy and homeland security adviser he has been the driving force behind the administration’s immigration crackdown, including its mass deportation program.

Wiles was the first woman to hold the job of White House chief of staff. Her departure from the West Wing’s top post comes as the administration braces for a Democratic-controlled Congress: Democrats won control of the House and Senate in Tuesday’s midterms, an outcome widely read as a repudiation of Trump’s second term, and the new majorities will arrive with subpoena power and plans for investigations.

Trump has kept a lower-than-usual public profile since the midterm defeat, with his only post-election public events focused on White House renovation work. On Friday he headed to Florida for his first trip outside Washington since the election, where he is expected to visit a technology conference at NASA’s Kennedy Space Center.

Miller takes over the chief of staff’s office on Monday, as the White House prepares for a new era of divided government and the investigations — and a possible impeachment vote against Pentagon chief Pete Hegseth — that the incoming Democratic majorities are expected to pursue.