Stephen Miller, one of Donald Trump's most radical advisors, is known for his unswerving defense of a resolutely anti-immigrant policy.
But a recently leaked trove of emails also shows him appearing to promote white supremacist views - prompting 25 Jewish members of Congress to demand his dismissal.
In a letter dated Friday, the lawmakers - all Democrats - wrote, "As Jewish members of Congress, we are calling on you to immediately relieve White House Senior Advisor Stephen Miller of all government responsibilities and dismiss him from your administration."
They added, "His documented support for white nationalist and virulently anti-immigrant tropes is wholly unacceptable."
More than 100 Democratic members of Congress had issued a similar plea after the emails were published last month by a non-profit association that monitors hate groups, the Southern Poverty Law Center.
In all, the SPLC obtained more than 900 emails sent in 2015 and 2016 by Miller to editors at the far-right Breitbart news website.
In the messages - whose authenticity Miller has not denied - he notably shares links to far-right websites and asserts a causal connection between immigrants and violence.
He urges the Breitbart editors to call attention to "The Camp of the Saints," a 1973 dystopian novel by French author Jean Raspail popular in far-right white nationalist circles.
It paints a dark story of mass migration from the Third World leading to the destruction of Western civilization.
Raspail's thesis is reminiscent of the so-called Great Replacement theory popular among the far-right: that the white European population is being steadily replaced by darker-skinned non-European immigrants.
"I was horrified by those emails and the content, but unfortunately I was not surprised," Kim Schrier, a Democrat from Washington state who was among the 25 signatories of the most recent protest letter, told NPR radio.
"I don't think any of us was surprised to hear that so much of the rhetoric" from Miller "was rooted in anti-Semitic, white nationalist rhetoric."
The fact that Miller himself is Jewish changes nothing, Schrier added.
"His behavior can still be white nationalist and anti-Semitic," the congresswoman said. "It is hate-speak, and it is wrong, no matter who it comes from."
Miller was an architect of the presidential decree barring nationals of several Muslim-majority countries from entering the US - one of the most controversial episodes of the Trump presidency.
For that and other reasons - including his equating of white nationalist marchers in Charlottesville, Virginia, with anti-racist demonstrators - Trump has been accused of racism and xenophobia, charges he has categorically rejected.
'Proud to be American'
Miller appears to have taken the controversy in stride. On Fox News, the president's favorite TV network, Miller insisted that the emails simply provided proof of his patriotism.
"There's nothing wrong in any of my emails... unless being proud to be American and standing up for American citizens is a crime."
Attempting to turn the tables, he suggested that the Democrats' calls for his dismissal aimed merely to "cover up the fact that there is... this vein of anti-Semitism that pulses through the Democratic Party."
But Democratic lawmakers are not the only ones denouncing Miller's views.
Last year, the rabbi of the California synagogue where Miller's family once worshiped, Neil Comess-Daniels, sharply criticized the Miller-influenced policy of separating migrant children from their families at the border with Mexico.
"From the Jewish perspective, the parent-child relationship is sacrosanct," he said in a sermon quoted by American news media. "Disrupting it is cruel. Mr Miller, the policy you helped to conceive and put into practice is cruel."
Katie McHugh, the former Breitbart journalist who released Miller's emails, went even further.
Describing herself in a CNN interview as a repentant former white nationalist, she said that Miller is "a white supremacist, I would say, because I believe his ideology is one of domination and control over people of color."
When the emails were published in November, the White House came to Miller's defense.
A presidential spokesman, Hogan Gidley, asked why "so many on the left consistently attack Jewish members of this administration."