When she ended her 2020 bid last week, Kamala Harris vowed to “keep fighting every day for what this campaign has been about...justice for the people. All the people.” The California senator wasted no time in following through, hinting at how she might seek to leverage her name recognition post-campaign. In a letter to the Trump administration Monday, Harris led her colleagues in a renewed call for the White House to fire Stephen Miller, the top Donald Trump aide who promoted white nationalist ideology in emails uncovered last month by the Southern Poverty Law Center. “Mr. Miller is unfit to serve in any capacity at the White House,” Harris wrote, according to a copy of the letter obtained by HuffPost, “let alone as a senior policy adviser.”

The letter—whose signatories include Harris’s former 2020 rivals Bernie Sanders, Elizabeth Warren, Amy Klobuchar, and Cory Booker—adds to the already intense pressure on the White House to relieve Miller of his duties, though the administration has given zero indication it plans to heed those calls. Miller, who has encouraged Trump’s immigration crackdown, has never made a secret of his nationalist, anti-immigrant worldview, evidenced in his reported proposal to release detained immigrants in sanctuary cities as a form of retaliation, and his alleged push to tax Mexico. “He is working behind the scenes, he has planted all of his people in all of these positions, he is on the phone with them all of the time, and he is creating a side operation that will circumvent the normal, transparent policy process” in order to push his agenda, a source told my colleague Abigail Tracy last year, highlighting the insidious ways in which Miller pushes his priorities.

Miller’s emails to the right-wing Breitbart News, sent ahead of the 2016 election while he worked for then-Alabama Senator Jeff Sessions, provided an even more granular look at the points of view he espouses. In them, Miller promotes the views of white supremacists like Jared Taylor, editor of the so-called “white advocacy” publication American Renaissance; links immigration to crime; and recommends a racist 1973 French novel suggesting immigrants would cause the downfall of western civilization as a corollary to current events. “It is simply appalling that a senior adviser to the President advanced parallels between this book and contemporary events,” Harris and others wrote Monday.

At least 75 House Democrats have also called for Miller’s removal, and the SPLC has circulated a petition pushing for him to be fired. But Republicans have mostly been silent on the matter, and the White House has stood by Miller amid the fallout. “I know Stephen,” deputy press secretary Hogan Gidley told the Hill last month, attempting to frame calls for his removal as somehow anti-Semitic “He loves this country and hates bigotry in all its forms.”

That in itself is a pretty good indication that the administration has no plans to sever ties with Miller, setting up a de facto confrontation between Trump and Harris that promises to play out as long as Miller remains on staff. In leading the charge, Harris is cementing her post-campaign position as a leading Trump antagonist. Before she entered the presidential race, Harris was perhaps best known for eviscerating now Supreme Court justice Brett Kavanaugh during his Senate confirmation hearing; months later, she did the same with attorney general William Barr. She may not get the chance to cross-examine Miller in practice, but in principle she’s once again setting herself against a figurehead that stands for everything she wishes to be known for fighting against.

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