Miller with Trump in August
US President Donald Trump announced on Friday that Stephen Miller, his deputy chief of staff, would replace Susie Wiles as chief of staff.
In a post on Truth Social, Trump said Wiles did an "outstanding job" and would be moved to the "Trump Political Operation".
The news comes after Republicans suffered a series of major defeats in the 2026 midterm elections, including losing control of both chambers of Congress.
Miller, considered the architect of Trump's hard-line immigration policy, has been a loyal ally of the president and served as a senior adviser to Trump during his first administration. Trump said he would take on the new role on Monday.
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Wiles gave her resignation to Trump on Thursday night, a US official told CBS News, the BBC's media partner.
Her resignation was related to Republican midterms defeats, three sources told CBS.
It was unclear if her deputies would remain at the White House.
In a statement, she said being on Trump's team was "the honor of a lifetime".
"I'm so proud to have been a part of what we've accomplished together from securing our border and cutting taxes to strengthening our economy and putting America First," she said. "While my role may be changing, my commitment to the President and the mission never will."
Wiles, 69, is seen as among the most powerful figures in the Trump administration and someone particularly close to the US president.
Asked last month whether Wiles could be replaced soon, Trump said there was "zero chance".
"Susie is here and she's gonna be here for a long time," he said.
Wiles recently battled cancer, announcing in September, six months after her diagnosis, that she was in remission.
During Trump's first and second term, Miller has been the architect of some of his most controversial immigration and deportation policies, which have sparked a backlash from Democrats.
One of Trump's closest aides, Miller stuck by the president following his 2020 election defeat, and followed Trump back into power last year.
Miller on left and Wiles on right
Wiles is not the only high-profile Trump official to leave this week following the midterm elections, which have prompted a reckoning among Republicans about how to address voters' rebuke of Trump's agenda.
Several justice department officials have also resigned, including John Eisenberg, the head of the department's National Security Division, and Jason Reding Quiñones, who was known for enforcing conspiracy probes into officials investigating Trump's handling of classified documents.
Democrats took to social media to criticise Trump's new pick, accusing him of doubling down despite voters' anger with his party's agenda.
Democratic Congressman Robert Garcia, who would lead the House Oversight Committee after Democrats take control of the chamber, said he would continue to investigate Miller and his "misconduct".
"Just days after the American people rejected his corrupt and lawless presidency, Donald Trump is doubling down. Stephen Miller is the architect of the unconstitutional ICE raids that have terrorized our communities and kidnapped and killed American citizens and immigrant families," he said, referencing US Immigration and Customs Enforcement.
Trump's communications director Steven Cheung called Miller "someone who has been with the President since the very beginning".
"There is no bigger advocate for the Trump agenda than Stephen, and he will help the Administration deliver on monumental victories for the rest of this historic second term," he said.
