President Donald Trump attacked Democratic Sen. Elizabeth Warren at a rally Thursday night over her claimed Native American heritage.

He mockingly called her "Pocahontas" and said he would give $1 million to the charity of her choice if she took a DNA test proving she is part Native American.

Trump's attacks on Warren are reminiscent of his role in the"birther" movement, in which he falsely claimed that President Barack Obama was not born in America.

President Donald Trump revived his attacks on Sen. Elizabeth Warren of Massachusetts and her purported Native American heritage at a campaign rally on Thursday night, mockingly calling her "Pocahontas" and calling on her to take a DNA test in exchange for a $1 million donation to the charity of her choice.

His attacks on Warren's heritage weren't new, but the addition of an offer of $1 million for DNA testing was reminiscent of Trump's favorite line of attack that contributed heavily to his rise in America's political conscience — birtherism.

Trump and Warren, a progressive stronghold in the Senate, have clashed bitterly before, most notably during the 2016 election cycle when he frequently called her "Pocahontas" in a jab at her heritage. In a series of May 2016 tweets, he wrote "goofy Elizabeth Warren didn’t have the guts to run for POTUS. Her phony Native American heritage stops that and VP cold."

The veracity of Warren's claimed Native American roots has been a subject of controversy since she first ran for Senate in 2012. Warren, who is originally from Oklahoma, maintains she is 1/32 Cherokee from her mother's side of her family.

But in absence of conclusive proof of her Cherokee roots in the form of ancestral birth certificates or DNA testing, her opponents have accused her of embellishing her heritage to benefit from affirmative action policies during her academic career as a law professor. (Warren did list herself as a "minority faculty member" when she taught at the the University of Pennsylvania and Harvard University, but she did not take advantage of affirmative action policies during her undergraduate career or law school.)

“Let's say I'm debating Pocahontas, right?” Trump said on Thursday. "I'm going to get one of those little kits ... and we will say, 'I will give you $1 million to your favorite charity, paid for by Trump, if you take the test and it shows you're an Indian ... and let's see what she does, right?"

Trump's attacks on Warren's heritage are reminiscent of the "birther" movement that thrust him into the political spotlight years ago when he waged a media campaign to try and prove former President Barack Obama was born in Kenya, the home country of his father, instead of in Hawaii.

Even after Obama released his long-form birth certificate proving he was born in Honolulu, Trump offered Obama $5 million for the charity of his choice if he released his "college records and applications, and if he gives his passport applications and records."

Warren fired back at Trump Thursday night in a tweet that referenced the Trump administration's controversial family separation policy.

"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," she wrote.

Earlier this year, Warren addressed her heritage before a Native American group.

"My mother's family was part Native American. And my daddy's parents were bitterly opposed to their relationship. So, in 1932, when mother was 19 and daddy had just turned 20, they eloped,” Warren said in a speech at the National Congress of American Indians in February.

"I get why some people think there's hay to be made here. You won't find my family members on any rolls, and I'm not enrolled in a tribe. And I want to make something clear. I respect that distinction."