Stephen Miller’s route to White House chief of staff ran from a liberal Jewish family in Santa Monica through conservative columns at Duke University and Trump’s 2016 campaign to what the Wall Street Journal describes as near-unprecedented power for a White House staffer, according to a Journal profile published Friday.

Trump announced Friday that Susie Wiles, his chief of staff and close ally, is leaving the White House to make way for Miller, the Wall Street Journal reported. Miller, a top adviser known for his hard-line approach to immigration, officially held the titles of deputy chief of staff for policy and homeland security adviser; the Journal reported that his title belied a sweeping role in shaping the president’s domestic and foreign policy agenda.

Miller grew up in a liberal Jewish family in Santa Monica, California, and was a conservative even in his high school years, gaining a reputation for complaining to conservative media personalities about perceived liberalism from his high school’s leadership, the Journal reported. At Duke University, he wrote for the school paper as a columnist, espousing conservative viewpoints and criticizing the institution’s liberal leanings. “Like countless other schools across the nation, we too are a leftist university,” Miller wrote in an early column titled “Welcome to Leftist University.”

Miller joined Trump’s 2016 campaign after working for Jeff Sessions, then a Republican senator from Alabama. Colleagues praised Miller for channeling Trump’s style and beliefs, and he gained prominence after writing the then-candidate’s acceptance speech for the Republican nomination in 2016. “Stephen is one of the most important people in the campaign,” campaign manager Paul Manafort said in a 2016 interview with the Journal. “He clearly understands Mr. Trump’s voice.” After Trump won election, Miller was appointed director of speechwriting in the White House.

After the Jan. 6, 2021, attack on the Capitol, many Trump allies abandoned the president. Miller did not: the Journal reported he helped draft Trump’s speech on the morning of Jan. 6 and, at the end of Trump’s first term, told others the president would be back.

After Trump lost re-election, Miller launched America First Legal, an organization that challenged initiatives enacted by the Biden administration and recruited Trump lawyers and Republican state attorneys general, according to the Journal. The group was backed by Mark Meadows, a former White House chief of staff, and pursued lawsuits opposing diversity policies at companies, many of which were later scrutinized by the Trump administration.

Trump supported the organization, saying in an email statement to the Journal at the time: “Conservatives and America First supporters badly need to catch up and turn the tables, which is why I applaud Stephen and Mark Meadows for rushing to fill this critical void.”

Miller has long played a key role in the president’s approach to immigration. In 2019, Trump told Miller, who had a reputation for hard-line immigration stances, “you’re in charge” of the administration’s immigration policy, the Journal reported that year. Miller helped identify immigration as a key campaign issue in Trump’s re-election bid.

In the current administration, the Journal reported, Miller has been the architect of an aggressive immigration policy that has included mass deportations and revocations of legal status. The enforcement campaign has so far brought illegal border crossings to their lowest level in decades, the newspaper reported.

Public sentiment has shifted this year, according to the Journal. After two Americans were fatally shot in Minnesota last winter during an immigration crackdown, weeks of protests erupted — protests the newspaper said likely contributed to Trump’s midterm loss this week. After Hispanic voters moved to Trump in the 2024 election, counties that were 80% or more Hispanic favored Democrats by 40 percentage points, the Journal reported.

Miller’s influence extends beyond immigration. The Journal reported last year that he has a staff of around 30 and has spearheaded the administration’s battles with universities over diversity policies and with law firms that have represented the president’s opponents. The newspaper also reported that Miller was the architect of deadly strikes in the Caribbean on boats allegedly transporting drugs.

The Journal reported that Miller was part of a meeting involving Meta chief executive Mark Zuckerberg and spoke with CEOs about an announcement on tariffs. Steve Bannon, a former Trump adviser, described Miller’s working style to the newspaper: “Stephen had the unique ability to take the president’s idea on complex topics and hammer through a set of policies that drive the action and deliver. He doesn’t overwhelm you with a charm offensive—it’s action.”