The Trump administration is known for its revolving door of staff members. White House senior policy adviser Stephen Miller, however, has outlasted many of Trump’s most high-profile hires. Along the way, he designed the first travel ban and advocated for family separations at the U.S.-Mexico border, among other anti-immigration policies. In November, leaked emails between Miller and Breitbart, the far-right website, obtained by Hatewatch, a publication of the Southern Poverty Law Center, revealed in writing what many observers suspected for years: Miller is also a white nationalist.

On Tuesday, Hatewatch published a new batch of the leaked emails, showing Miller “siding with white nationalists and other extremists on the issue of Deferred Action for Childhood Arrivals, more commonly known as DACA.” He is vehemently opposed to the United States providing a path to citizenship for undocumented immigrants who came to America with their parents as young children but who have not yet obtained citizenship.

Hatewatch obtained 900 emails from Katie McHugh, a former Breitbart editor, who told the SPLC she shared them to expose the “evil” roots of the Trump administration’s policies. They were sent while Miller was an aide to former Sen. and Attorney General Jeff Sessions.

In the emails, Miller is obsessed with “the great replacement,” an idea popularized by white nationalist groups claiming that immigrants are going to soon outnumber native-born Americans. Hatewatch points out that the concept has inspired white supremacist terrorism, including an attack on a New Zealand mosque. Miller mentioned the theory in a 2015 email criticizing former Florida Gov. and presidential candidate Jeb Bush: “Jeb has mastered the art of using immigration rhetoric to sound ‘moderate’ while pushing the most extremist policies.” Miller later claimed Bush wanted to use “immigration to replace existing demographics.”

Miller also told McHugh that DACA “provides illegal youth (one of the single strongest pull factors for entering and remaining illegally) with both work permits and generous free cash tax credits.”

He admonished Republicans who expressed sympathy for the plight of DACA recipients, also known as “Dreamers”: “Demanding DREAMers be given citizenship because they ‘know no other home.’ That principle is an endorsement of perpetual birthright citizenship for the foreign-born,” Miller wrote in the email. “Not only will the U.S.-born children of future illegal immigrants and guest workers be made automatic U.S. citizens, but their foreign-born children will too because, as [former Republican House Majority Leader Eric] Cantor said, ‘Our country was founded on the principle.’ ”

In other emails to Breitbart staff, Miller forwarded an interview with anti-feminist activist Phyllis Schlafly, in which she argued, according to Hatewatch, that “undocumented immigrants should be shipped out on trains to ‘scare out the people who want to undo our country.’ ”

Miller was also angry when Fox News Chairman Rupert Murdoch tweeted that “Mexican immigrants, as with all immigrants, have much lower crime [rates] than native born,” a view Miller considered insufficiently anti-immigrant. He argued that it is time to “lift the taboo” on expressing his belief that Latino immigrants are less likely to be upwardly mobile than whites.

Immigration reform, especially protections for undocumented immigrants who arrived in the United States as children, once had broader support among Republicans.

When the party released its analysis of the 2012 election, the 100-page “autopsy” document warned that “we must embrace and champion comprehensive immigration reform. If we do not, our Party’s appeal will continue to shrink to its core constituencies only.” The report added that “comprehensive immigration reform is consistent with Republican economic policies that promote job growth and opportunity for all.” Sen. Lindsey Graham, R-S.C., was an original sponsor of the DREAM Act. As McClatchy’s Emma Dumain recalled last year, Graham’s primary opponents in the 2014 election taunted him for it, calling him “Lindsey Grahamnesty.”

At the time, Graham stood firm on his position. Now, Dumain observes, he “is aligning himself with conservative immigration hardliners,” moving closer to Miller’s position.

More than 150 Democratic politicians have demanded that Miller be fired or resign since the initial publication of the Brietbart emails, according to reporting from HuffPost, but Republicans have remained largely silent.

Read the full Hatewatch series here.