Sen. Elizabeth Warren ripped President Donald Trump on Twitter after he insulted her at a campaign rally in Montana.

On Thursday, Trump repeated his use of “Pocahontas,” a slur that he has used to demean Warren’s claiming Native American heritage.

“Pocahontas, they always want me to apologize for saying it,” Trump said. “Pocahontas, I apologize to you, to you I’ll apologize. To the fake Pocahontas I won’t.”

Trump also pledged he would give $1 million to a charity of Warren’s choice if she took a DNA test.