Sen. Kamala Harris (D-Calif.) and a large group of Democratic senators have signed a letter that will be sent to the White House on Monday calling on President Donald Trump to fire senior adviser Stephen Miller in light of leaked emails showing the extent of his white nationalist beliefs.

“We write to demand the immediate removal of Stephen Miller as your advisor,” states the letter, a copy of which was provided to HuffPost by Harris’ office.

The leaked emails, the letter says, show that “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.”

“Simply put,” the letter continues, “Mr. Miller is unfit to serve in any capacity at the White House, let alone as a senior policy adviser.”