Homeland Security Secretary Markwayne Mullin has struggled to overcome doubts about his leadership among hard-liners in President Trump's base, despite toughening his language on immigration and increasing arrests and detentions. The White House recently withdrew the nomination of Mr. Mullin's ally Lance Schroyer for ICE director, with border czar Tom Homan reportedly frustrated by Mullin's advocacy for Schroyer, who had no ICE experience. D.H.S. and the White House did not respond to requests for comment.

Mark Morgan, who ran U.S. Customs and Border Protection during Trump's first term, said Mullin's support for Schroyer gave the impression he was choosing a friend rather than the best-qualified person, noting Schroyer was from Mullin's home state of Oklahoma and had been part of his security detail. It is not the first time Mullin has been overruled; earlier this year ICE halted traffic stops after a shooting in Maine, but Trump quickly reversed the pause.

Mullin further alienated immigration hawks at the National Governors Association conference in August by emphasizing nearly a million people received U.S. citizenship during the administration and appearing to support immigration reform. After criticism, he posted on X: "NO amnesty for illegal aliens. Ever. We are a nation of laws."