Washington — Top Trump adviser , who is set to take over the White House chief of staff role on Monday, has driven President Trump’s most controversial immigration policies during both of his administrations. 

Mr. Trump announced the staffing shake-up on Friday, calling Miller one of his “most trusted” advisers. Miller replaces Susie Wiles, who has been his chief of staff throughout his second term. 

The move comes after Republicans suffered and as Democrats plan sweeping investigations into the administration’s actions, including its immigration enforcement policies. 

Miller was the architect behind many of those policies and also championed the administration’s immigration enforcement expansion, which has been supported by approximately $170 billion that congressional Republicans allocated for immigration enforcement and border security in the One Big Beautiful Bill Act, which became law in July 2025. 

During Mr. Trump’s first term, Miller helped develop and publicly defend the administration’s that restricted entry by nationals of several Muslim-majority countries. The travel ban led to protests around the U.S. and legal challenges. A third iteration of the ban was upheld by the Supreme Court in 2018. 

He was a of the administration’s 2018 zero-tolerance immigration policy, which resulted in thousands of family separations, and he pressed for dramatic reductions in refugee admissions. The administration repeatedly lowered the annual refugee admissions ceiling, ultimately setting it at 15,000 for fiscal year 2021, a record low at the time. Under former President Barack Obama, the ceiling was 110,000 for fiscal year 2017. 

Miller also penalizing legal immigrants who received public benefits and making it harder for them to obtain citizenship.  

In Mr. Trump’s second term, Miller pushed Immigration and Customs Enforcement to make per day. In May 2025, Miller publicly demanded a dramatic increase in daily arrests, placing pressure on ICE leadership and expanding enforcement beyond immigrants who had been convicted of serious crimes. 

He also that the National Guard be deployed to support mass deportations. 

Miller’s arrest targets were part of a sweeping expansion of enforcement in communities, workplaces and immigration courts. Detentions of immigrants without criminal histories , and increased ICE activity sparked protests across the country.  

The longtime Trump adviser also championed the use of a wartime law — the — to bypass due process and quickly deport to El Salvador, where they were held in a notorious maximum-security prison, known as CECOT. The deportations set off a legal battle, and the Supreme Court blocked the government from immediately deporting the Venezuelans without giving them an opportunity to challenge their removal. 

As part of the administration’s deportation efforts, Miller has supported an aggressive expansion of . The administration has deported immigrants to countries where they have no citizenship or family ties, . 

In May 2025, Miller said the administration was actively considering suspending the constitutional mechanism that allows detainees to challenge their confinement in court. 

At a March 2026 conference in Miami, Miller argued that military force, rather than traditional criminal law enforcement alone, was needed to defeat cartels. 

Miller appeared alongside Mr. Trump in the Oval Office this summer as he to refuse citizenship to some children born in the United States, after the Supreme Court his earlier executive order aiming to end birthright citizenship.