Rep. Alexandria Ocasio-Cortez (D-New York) called for White House advisor Stephen Miller‘s resignation after leaked emails showed him privately promoting stories from white nationalists and being extremely anti-immigration.

The emails, which were sent to Breitbart News in 2015 and 2016, were published in a report by the Southern Poverty Law Center.

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Katie McHugh, who was an editor for Breitbart from April 2014 to June 2017, leaked the emails to Hatewatch, a branch of the SPLC in June. McHugh was fired from Breitbart in 2017 after posting anti-Muslim tweets, but has since renounced the far right.

Ocasio-Cortez tweeted after the report was published, “Stephen Miller, Trump’s architect of mass human rights abuses at the border (including child separation & detention camps w/ child fatalities) has been exposed as a bonafide white nationalist.”

She added, “He’s still at the White House shaping US immigration policy. Miller must resign. Now.”

Hatewatch reviewed more than 900 previously private emails Miller sent to Breitbart editors from March 4, 2015, to June 27, 2016, and found that more than 80 percent of the emails related to or appeared on threads about race or immigration.

Among other things, Miller recommended in an email that Breitbart write about The Camp of the Saints, a racist French novel by Jean Raspail. The novel is known for fictionalizing the “white genocide” or “great replacement” myth into a violent and sexualized story about refugees.

Elizabeth Moore, a spokesperson for Breitbart, told Hatewatch “you now have an even better idea why we fired her,” but added that politicians try to pitch stories frequently.

“It is no surprise to us that the SPLC opposes news coverage of illegal-immigrant crime and believes such coverage is disproportionate, especially when compared to the rest of the media, which often refuse to cover such crimes,” Moore said.

She added, “No one in our senior management has read the book, Camp of the Saints, but we take The New York Times at their word that it is a ‘cautionary tale,’ and the National Review at theirs that ‘the central issue of the novel is not race but culture and political principles.'”

White House Press Secretary Stephanie Grisham denounced the report in a statement saying that the SPLC is “an utterly discredited, long debunked far-left smear organization” and that they are “beneath public discussion.”