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.

President Trump appears to mock Sen. Elizabeth Warren during a rally in Montana, promising to ask her to complete a test for the results of her heritage.

“But we have to do it gently because we’re in the MeToo generation.” https://t.co/5PuhKcpbSw pic.twitter.com/KNcOONPkbN — MSNBC (@MSNBC) July 6, 2018

“But we have to do it gently because we are in the #MeToo generation,” Trump said, in reference to women speaking out about sexual harassment.

“And we will very gently take that kit and we will slowly toss it, hoping it doesn’t hit her and injure her arm,” he said.

In response, Warren tweeted that while “you obsess over my genes,” to discuss the Trump administration’s family separation policy at the U.S.-Mexico Border.

ICYMI: Warren Rebukes Trump’s ‘Pocahontas’ Nickname in Speech to National Congress of American Indians

Warren said Trump’s administration was using DNA tests on children at the U.S.-Mexico border “because you ripped them from their mamas & you are too incompetent to reunite them in time to meet a court order.”

A U.S. District Court judge last week ruled that the administration had until July 10 to reunite migrant children under the age of 5 with their parents.

“Maybe you should focus on fixing the lives you’re destroying,” she tweeted.

Hey, @realDonaldTrump: While you obsess over my genes, your Admin is conducting DNA tests on little kids because you ripped them from their mamas & you are too incompetent to reunite them in time to meet a court order. Maybe you should focus on fixing the lives you’re destroying.

— Elizabeth Warren (@elizabethforma) July 5, 2018

Warren visited a facility in McAllen, Texas where migrants were being held in chain-link cages and she has been a vocal critic of the policy.

Warren is also up for re-election this year in Massachusetts, a race that Inside Elections with Nathan L. Gonzales rates as Solid Democratic.

Watch: Thousands March in DC to Protest Family Separation