Who is Stephen Miller? The immigration hardliner tipped to be Trump's security chief

US President Donald Trump has said his deputy chief of staff, Stephen Miller, is a top contender to become the next national security advisor following the removal of Mike Waltz.

Speaking aboard Air Force One on Sunday, Trumpsaid: "Stephen Miller is at the top of the totem pole. I think he sort of indirectly already has that job. Because he has a lot to say about a lot of things. He's a very valued person in the administration."

Miller is widely seen as the architect of the Trump administration’s hardline immigration agenda and remains one of the president's most influential advisors.

From immigrant roots to immigration hardliner

Born in 1985 in Santa Monica, California, Miller was raised in a liberal-leaning Jewish family. According to Business Insider, his relatives fled anti-Jewish pogroms in the Russian Empire in the early 20th century.

In a 2018 Politico article, Miller's uncle expressed dismay at his nephew's political stance, saying Miller’s anti-immigration policies "repudiate the very foundation of our family’s life in this country".

Miller studied political science at Duke University, where he gained notoriety as a conservative commentator and appeared on outlets such as CNN and Fox News's 'The O’Reilly Factor'. 

He later worked for Republican lawmakers Michele Bachmann, John Shadegg, and notably Senator Jeff Sessions - a tenure that shaped his views on immigration.

A longtime Trump ally

Miller played a key role in Trump's 2016 campaign as a senior policy advisor and speechwriter, penning Trump's keynote address for the Republican National Convention.

He went on to serve as a senior advisor in Trump’s first administration for the full four years, focusing initially on domestic policy before turning his attention almost exclusively to immigration.

He was instrumental in controversial policies such as the Muslim travel ban and the family separation policy at the US-Mexico border. Former House Speaker Kevin McCarthy once referred to Miller as "Trump's brain", according to The New York Times.

Now serving as deputy chief of staff for policy and homeland security advisor, Miller has led the administration's intensified crackdown on immigration.

This has included mass deportations, even of some legal US residents. One such case involved Kilmar Abrego Garcia, a permanent resident whose deportation to El Salvador was later deemed unlawful.

The administration has also targeted foreign students involved in protests against Israel’s war on Gaza on university campuses. According to Axios, Miller strongly advocates for expedited deportations without court hearings - a position that has drawn significant criticism.

Miller doubled down on that stance on Monday, posting on X that legal blocks on mass deportations amounted to "judicial tyranny".

Miller’s extreme views have drawn condemnation from both political opponents and former colleagues.

Olivia Troye, a former White House official who worked with him, said in an interview on the podcast 'To The Contrary': "He is a horrible human being… someone who has gone all in, down the rabbit hole, on extremism."

"In his mind, there would be no migrants, immigrants, or any mixed race in our country," she added.

Despite - or because of - his hardline record, Miller has strong support within Trump’s inner circle. Multiple reports suggest he is a leading candidate for the national security advisor post, a role that would give him broader authority over key aspects of US domestic and foreign policy.