Shortly after 4:30 p.m. on April 8, Rep. Ilhan Omar (D-Minn.) fired off the 21-word tweet labeling White House senior policy adviser Stephen Miller a “white nationalist,” and within hours, conservative Twitter was aflame.

Omar’s blunt critique of one of President Trump’s most trusted aides immediately drew the ire of prominent figures on the right, who pointed out that Miller is Jewish and accused the freshman representative of anti-Semitism — a charge she has repeatedly faced over past comments about Israel’s ties to U.S. leaders.

On Tuesday, Omar resurrected her incendiary tweet. Her characterization of Miller had been accurate, she tweeted, and now there was proof.

Earlier in the day, the Southern Poverty Law Center released a report titled, “Stephen Miller’s Affinity for White Nationalism Revealed in Leaked Emails,” which has since sparked intense blowback against Trump’s top immigration adviser, prompting calls from Democratic leaders for him to resign or be fired. After reviewing more than 900 emails Miller sent to editors of the conservative site Breitbart between 2015 and 2016, the report’s writer noted he had been “unable to find any examples of Miller writing sympathetically or even in neutral tones about any person who is nonwhite or foreign-born.”

“This type of racism and hatred has no place in our government,” Omar wrote Tuesday. “Miller needs to step down. Now.”

Miller did not respond to a request for comment early Wednesday regarding the backlash. A White House official, speaking on the condition of anonymity to comment on a sensitive matter, told The Washington Post an email Wednesday that Omar’s recent comments “are the latest example of her well-known, well-documented, rampant anti-Semitism,” describing them as “ignorant and hateful attacks on a Jewish staffer.”

"While Mr. Miller condemns and repudiates bigotry, Rep. Omar continues her vile attacks on Israel and the Jewish People,” the official said.

In an email to The Post Tuesday, White House press secretary Stephanie Grisham said she had not seen the SPLC report but called the civil rights nonprofit an “utterly-discredited, long-debunked far-left smear organization.”

“They are beneath public discussion, even in The Washington Post,” Grisham said.

Omar was among numerous Democrats, including at least two 2020 presidential candidates, on Tuesday to denounce Miller, who has been described by The Post as “the singular force behind the Trump administration’s immigration agenda.”

“Stephen Miller’s white nationalist views are a danger to the American people,” tweeted Sen. Bernie Sanders (I-Vt.). “We are going to defeat this hateful administration and everything it stands for.”

Sanders’s fellow presidential hopeful Julián Castro slammed Miller as a “Neo-Nazi.”

“Donald Trump put a Neo-Nazi in charge of immigration policy,” the former housing secretary wrote on Twitter. “Both him, and Stephen Miller, are a shame to our nation.”

Meanwhile, Reps. Alexandria Ocasio-Cortez (D-N.Y.) and Earl Blumenauer (D-Ore.) echoed Omar’s demand that Miller leave the White House.

The trove of emails were given to the SPLC by Katie McHugh, a former Breitbart staffer who was fired over anti-Muslim tweets in 2017 and has since renounced the far right. Tuesday’s report marks the first in a series about the emails intended to “reveal Miller’s alignment with white nationalist thought and far-right extremism,” the center wrote.

The emails have renewed scrutiny of Miller, who is credited with helping create some of Trump’s most controversial immigration policies, ranging from the executive order banning travel to the United States from several Muslim-majority countries and the family separation policy.

Over a 15-month period ahead of the 2016 presidential election, Miller communicated regularly with Breitbart staffers and his emails were characterized as attempts to influence the site’s coverage, according to the SPLC report. Miller’s emails reportedly showed him encouraging the conservative site to run anti-immigrant stories. He also referenced content from websites such as VDARE, a known platform for white nationalists; American Renaissance, a white-supremacist publication; and Infowars, the report said.

“The most important takeaway for me is that Stephen Miller found the basis for his ideas on websites that traffic in hate, and made it clear in his emails,” SPLC investigative reporter Michael Edison Hayden, who wrote the report, told The Post’s Kim Bellware.

In a statement to the SPLC, a spokesperson for Breitbart downplayed the communications, describing them as “three- to four-year-old emails, many previously reported on, involving an individual whom we fired years ago for a multitude of reasons, and you now have an even better idea why we fired her.”

The spokesperson added that “it is not exactly a newsflash that political staffers pitch stories to journalists — sometimes those pitches are successful, sometimes not.”

Still, social media exploded with reactions to the leaked emails Tuesday, and soon Miller was a top trending term on Twitter. While many remarked that the report’s revelations were unsurprising given Miller’s track record as a White House senior adviser, others argued that the emails provided evidence to support the previous accusations leveled against him.

“White people being snarky about the reporting on Stephen Miller’s emails — ‘oh, duh, we KNEW this’ — are undermining a key aspect of combating white supremacy,” poet Saeed Jones tweeted.

It didn’t take long for people to recall Omar’s April tweet and the barrage of criticism she received for penning it. Omar was lambasted at the time by Donald Trump Jr., Rep. Lee Zeldin (R-N.Y.) and other conservatives, who viewed her commentary on Miller’s immigration policies as another example of the congresswoman targeting Jews. Jeff Ballabon, a conservative commentator and Trump campaign adviser, argued then that Omar is “more dangerous” than former Ku Klux Klan leader David Duke and Nation of Islam leader Louis Farrakhan, The Post’s Meagan Flynn reported.

“Remember when Ilhan Omar called Stephen Miller a white nationalist and some in the media straight up called her an ‘anti-semite’, even though she was telling the truth?” a Twitter user wrote. “You all owe her an apology.”

But others suggested Miller losing his job and Omar getting an apology were both unlikely outcomes.

“Not holding my breath for Miller’s firing — or for his cronies to apologize to Rep Omar,” one person tweeted. “For them it’s a positive that Miller proudly promotes White supremacy as policy.”

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Despite President Trump's attacks against Rep. Ilhan Omar (D-Minn.), many of her Minnesota constituents say that it has only made their support of her stronger. (Drea Cornejo/The Washington Post)