As a young conservative in liberal Santa Monica, Calif., Stephen Miller clashed frequently with his high school, often calling in to a national radio show to lambaste administrators for promoting multiculturalism, allowing Spanish-language morning announcements and failing to require recitation of the Pledge of Allegiance.

Miller’s outrage did not appear to subside after he graduated. As a Duke University sophomore, Miller penned a column, titled “Santa Monica High’s Multicultural Fistfights,” in which he ripped his alma mater as a “center for political indoctrination.”

“The social experiment that Santa Monica High School has become is yet one more example of the dismal failure of leftism and the delusions and paranoia of its architects,” Miller wrote in the 2005 article for the conservative magazine FrontPage.

In the years before he became a top adviser to President Trump and a leading West Wing advocate for the executive order temporarily halting entry into the United States from seven majority-Muslim countries, Miller was developing his skills as a culture warrior and conservative provocateur eager to condemn liberal orthodoxy – particularly on matters of race and identity. Like Trump, Miller forged that identity while immersed in liberal communities, giving him cachet with fellow conservatives for waging his battles on opposition turf.

Starting as a teenager, with his frequent calls to the nationally syndicated “Larry Elder Show,” Miller made a name for himself in conservative media circles for his willingness to take controversial stands and act as a champion for those on the right who felt maligned by a culture of political correctness.

He produced a canon of searing columns on race, gender and other hot-button issues and, at Duke, became known to Fox News viewers as a leading defender of the white lacrosse players wrongfully accused of raping a black stripper. By his late 20s, Miller was a key aide to then-Sen. Jeff Sessions, R-Ala., helping to torpedo a long-sought goal of immigrant advocacy groups to put millions of unauthorized Hispanic immigrants on a path to citizenship.

Today, at 31, he has emerged alongside former Breitbart News chief Stephen Bannon as a chief engineer of Trump’s populist “America first” agenda that has roiled the Washington debate over immigration and trade and sparked alarm among traditional U.S. allies abroad.

Miller, whose White House title is senior adviser to the president for policy, has been at Trump’s side for more than a year, joining his campaign in January 2016 when Sessions, who was sworn in Thursday as attorney general, was one of the only Republican officials to endorse the businessman’s candidacy.

While Trump at times revamped his campaign leadership, with Bannon joining relatively late in August 2016, Miller remained a steady presence whose profile and influence grew over time.

He wrote some of Trump’s most strident speeches during the campaign, including his Republican National Convention acceptance address in which Trump declared that “nobody knows the system better than me, which is why I alone can fix it.”

And Miller sometimes served as the warm-up act for Trump at his large campaign rallies, including a rip-roaring speech in Wisconsin during the Republican primary when Miller thrashed Trump’s chief rival, Sen. Ted Cruz, R-Texas, for supporting increases in legal immigration that would result in more Muslims entering the country – a position Miller charged that Cruz held with “no regard, no concern” for how it would “affect the security of you and your family.”

After reports of Miller’s central role crafting the order imposing a 90-day ban on citizens of Iraq, Syria, Iran, Libya, Somalia, Sudan and Yemen from entering the United States, the young aide has drawn uncomfortable new scrutiny. MSNBC’s Joe Scarborough, host of the “Morning Joe” program that is a Trump favorite, recently blasted Miller as a “very young person in the White House on a power trip thinking that you can just write executive orders and tell all of your Cabinet agencies to go to hell.”

For Miller, though, working in the Trump White House is a natural culmination of his young career – a chance to work for a president who appears to share his zeal for angering political foes.

“The way that people on the left abuse and slam people on the right – that’s probably the thing that’s most concerned Stephen,” said Elder, whom Miller describes as a mentor. “The lack of fairness. The left-wing dominance in academia. The left-wing dominance in the media. The left-wing dominance in Hollywood.”

Miller said he rejects the “provocateur” label, saying it suggests that his intentions are to seek attention rather than what he says is his true goal: “to battle against slim odds, a stacked deck and powerful entrenched forces, in pursuit of justice.”