Senior Donald Trump adviser Stephen Miller made a confrontational appearance at the White House press briefing on Wednesday, announcing support for a bill that would slash immigration levels and sparring with reporters who asked critical questions.

Existing policies around legal immigration, Miller said, led to “significant reductions in wages for blue collar workers.” CNN reporter Jim Acosta, Miller said, had “a cosmopolitan bias.” The poem on the Statue of Liberty about “huddled masses yearning to breathe free,” he said, was “added later.”

The appearance made waves in Washington, but Miller’s no stranger to controversies like these — indeed, he’s one of the key architects of the anti-immigration agenda that’s key to Trumpism.

Amid staff shakeups and tumult, Miller has largely flown under the radar since the early days of the Trump administration, when he appeared on television defending the president’s travel ban.

His public reemergence should serve as a reminder to those who haven’t been following the immigration issue closely that, while issues like health care and Russia may have dominated headlines in recent months, the hardline anti-immigration views that defined Trumpism on the campaign trail have been present in administration policy all along.

The ideas of Miller and his allies — like chief strategist Steve Bannon and Attorney General Jeff Sessions — are very much still driving the immigration policy agenda inside the White House. And though Miller was publicly promoting a bill that appears likely to fail, the real action is in the executive branch.

That’s where Miller and like-minded advisers have been pushing their and Trump’s agenda on immigration in lower-profile, less-headline-grabby ways in the Justice Department and Department of Homeland Security. Miller’s base-pleasing anti-immigration positions have been the throughline of Trumpism all along.

Where Stephen Miller came from

Before Trump ran for president, the most prominent immigration hardliner in national politics was Sen. Jeff Sessions (R-AL).

Like much of the right, Sessions wanted a crackdown on unauthorized immigrants and opposed any proposals to grant any of them legal status in the US. But in contrast to most Republicans, who professed to be perfectly thrilled with legal immigration, Sessions wanted less of that too. He argued that allowing too many foreigners in ended up hurting Americans born here, both economically and culturally.

The key staffer shaping Sessions’s quest was Stephen Miller, a young aide. Born and raised in southern California, Miller distinguished himself by taking provocative and racially inflammatory stances from an early age. Then, in Sessions’s office, Miller became known among Washington reporters for sending out constant email blasts filled with anti-immigration talking points. But while Sessions had allies in the conservative media — for instance, Steve Bannon’s Breitbart News — he and his views were far from the halls of power, with both Democratic and Republican elites united against them.

Trump changed all that. From his very first campaign speech, in which he said that Mexico was sending “rapists” to the US, it was clear that he was an enormously promising ally to the small but passionate Sessions/Miller wing of Republicans. This became even clearer in December 2015, when Trump shocked the political world by calling for “a total and complete shutdown of Muslims entering the United States until our country's representatives can figure out what the hell is going on.”

Naturally, Miller joined the Trump campaign the very next month. Once on board, he became a “warm-up act” for Trump himself, delivering red meat opening speeches at rallies across the country, and also helped craft some of Trump’s own few scripted speeches.

He was rewarded for all this with a very plum White House job — just 31 years old, he’d be a senior adviser to the president for policy, with rank equal to famous figures of past administrations like Karl Rove, David Axelrod, and Valerie Jarrett. Meanwhile, his ally Steve Bannon was named chief strategist, and his former boss Jeff Sessions was nominated for attorney general. This trio of like-minded hardline immigration critics have been shaping national policy ever since.

This is what Trumpism is all about

Miller and his allies got by far the most attention back in the earliest days of the administration, when they crafted the initial version of Trump’s travel ban. They drew up a remarkably extreme policy with hardly any consultation from the agencies that would implement it or the lawyers who’d be tasked with defending it, and made it go into effect immediately.

It threw airports all over the country into chaos, caused massive protests, and was soon blocked in the courts. A very scaled-back version eventually was allowed to go into effect, but the initial fiasco was an embarrassment for the young administration.

But Miller and his views haven’t been marginalized — far from it.

Instead, in much lower-profile ways, while health care and Russia have been grabbing all the headlines, administration officials like Attorney General Jeff Sessions and Trump’s first Secretary of Homeland Security John Kelly have been enacting hardline immigration policies all along. (In fact, Trump was so pleased with how Kelly had handled his job that he recently named him chief of staff.)

Indeed, as my colleague Dara Lind has been writing, this is an area in which the administration has actually been effective at enacting Trump’s wishes:

They’ve instructed prosecutors to be far more aggressive in charging immigration offenses.

They’ve moved to block “sanctuary cities” from getting federal funds.

And they’ve granted far greater latitude to immigration enforcement officers in the field.

We see the impact of all this in, for instance, a late July raid in which 650 unauthorized immigrants were arrested — but only 30 percent of them had been specifically targeted. As Lind explains, this is a big change from Obama-era policies, which generally instructed ICE agents to only arrested people they had identified to target in advance.

So yes, Miller made a prominent public reappearance at the White House press briefing this week. But he and his policies have never really gone away. All along, they’ve been core to the Trump administration’s policies and goals.