The Huff Post reported Monday that more than half of the Democrats in the U.S. Senate are demanding the “immediate removal” of Stephen Miller from the White House.

Miller, a senior advisor to President Donald Trump who helps guide his immigration policy, has been linked to white nationalist beliefs.

Sen. Kamala Harris (D-Calif.) and a group of Democratic senators have signed a letter asking for Miller’s firing.

“We write to demand the immediate removal of Stephen Miller as your advisor,” states the letter, which was provided to HuffPost by Harris’ office. Hawaii Sen. Brian Schatz is not identified as a signatory to the letter, but his colleague, Mazie Hirono, was reported in November as calling for Miller to move on.

Last month, it was also reported that more than 100 House lawmakers sent a similar letter to the White House regarding Miller. They included House Judiciary Chairman Jerrold Nadler (D-New York).

Reps. Tulsi Gabbard and Ed Case were not signatories to the House letter.

Rep. Alexandria Ocasio-Cortez (D-N.Y.), who did sign the letter, also has an online petition targeting Miller.