In August, for his 40th birthday, Stephen Miller was thrown a surprise party fit for the most important staffer in Trump’s government. Cabinet secretaries (Marco Rubio, Scott Bessent, Kristi Noem), fellow West Wing officials (including Susie Wiles and James Blair), and MAGA luminaries like Fox’s Laura Ingraham and the commentator Mark Levin all gathered to fete him at Ned’s, the swank members-only club a block from the White House.

While Miller’s birthday bash reflected his D.C. caste—one attendee told me that it cemented his stature in the West Wing—one couldn’t help but notice that zero members of Congress, aside from Speaker Mike Johnson, were in attendance, symbolic of his standing on the Hill. While Miller spent nine years on the Hill, including as an aide to then-Senator Jeff Sessions, he didn’t exactly move over to 1600 Pennsylvania with a massive amount of goodwill. Even in his 20s, he was oddly intense, known for fringey sermons on the dangers of immigration that prompted plenty of eye rolls among his fellow Republican comms directors. Miller did see some early success, however. When the Gang of Eight proposed its immigration reform bill in 2013, Miller was instrumental in making sure it was dead on arrival in the House. His persistence paid off. He found a champion in Trump, who embraced Miller early on in his first campaign, and the party has largely come around to his position on immigration. Now, in Trump’s second term, Miller has attained a level of clout that has unsettled even some Republicans on the Hill. As the face of the administration’s most controversial immigration policies—deploying the military to U.S. cities, instituting deportation quotas for ICE, greenlighting indiscriminate arrests of anyone suspected of being undocumented—he has delighted in sparring with the media in defense of Trump. But his public language has become darker, too. In recent weeks, he has labeled left-wing protesters as terrorists and described unfavorable judicial rulings as “insurrection”—a position Trump is contemplating too, having used the same term to describe a small ongoing protest at a single Portland ICE facility. In private, several Republicans have told me that they’re worried about Miller’s policies, tactics, and stated legal rationales. “In some cases, I think he has gone too far,” one G.O.P. senator told me. A House member who described themselves as a “law and order” Republican said that “a large number of Republicans in the House are a little concerned that Stephen has dragged the president so far in one direction.” The lawmaker pointed to ICE raids sweeping up workers with no criminal records and the administration’s attempts to send the National Guard into places like Portland and Chicago. “It hasn’t surprised a lot of us that the courts have ruled against the president,” this person said. Miller’s legally questionable policy proposals include “looking at” suspending habeas corpus, the constitutionally guaranteed right to challenge one’s detention, on the grounds of an immigrant “invasion” that repeated court rulings have found not to exist. He’s sought to designate Antifa as a “domestic terrorist organization” even though no law provides for such a classification. This kind of constant pushing of the law’s limits is okay, Republicans tell me, so long as the administration adheres to court rulings. But Miller has also gone after judges who have issued adverse rulings. He called a judge’s order to turn around a deportation flight of Venezuelans “unlawful” as the administration ignored it. He also helped slow-roll compliance with the Supreme Court’s order to “facilitate” the return of Kilmar Abrego Garcia after the Maryland resident’s mistaken deportation to El Salvador. More recently, he accused a Trump-appointed judge of “egregious and thunderous violations of constitutional order” for blocking Trump’s federalization of the Oregon National Guard. And just this week, in fact, Miller floated the use of the Insurrection Act to get around such orders. He also surfaced the fringe idea that the administration can ignore courts’ immigration rulings because the issue is outside the judiciary’s purview—a legal theory known as “plenary power.” Still, Miller’s defenders, such as Senator Eric Schmitt, say he’s doing a “great” job and has legal justifications for his actions.