(JTA) — Bernie Sanders was among five Democratic presidential candidates who signed a letter from 27 U.S. senators calling on President Donald Trump to fire White House senior policy adviser Stephen Miller over his white nationalist beliefs.

The other candidates to sign on are Sens. Elizabeth Warren of Massachusetts, Cory Booker of New Jersey, Amy Klobuchar of Minnesota and Michael Bennet of Colorado. Sen. Kamala Harris, who dropped her candidacy, is the lead signatory.

“We write to demand the immediate removal of Stephen Miller as your adviser,” said the letter sent to Trump on Monday, the Huffington Post first reported. The letter was provided to the news website by Harris’ office.

“What is driving Mr. Miller” is “not national security, it’s white supremacy — something that has no place in our country, federal government, and especially not the White House,” the letter said, according to the Huffington Post. It continued: “Simply put, Mr. Miller is unfit to serve in any capacity at the White House, let alone as a senior policy adviser.”

Last month, the Southern Poverty Law Center published hundreds of emails sent by Miller to a reporter at the conservative Breitbart News, many of them racist and anti-immigrant in nature.

Many of the 900 emails sent from March 2015 to June 2016 “showcase the extremist, anti-immigrant ideology that undergirds the policies he has helped create as an architect of Donald Trump’s presidency,” according to the center’s report. More than 80 percent of the emails relate to race or immigration.

Miller, who is Jewish and a hardliner on immigration — his ancestors were immigrants to the U.S. — did not write sympathetically or neutrally about nonwhite or foreign-born people.