Massachusetts Sen. Elizabeth Warren released the results of a genetic test showing her Native American ancestry dating back “six to ten generations” ahead of a possible 2020 presidential run.

“In the senator’s genome, we did find five segments of Native American ancestry with very high confidence where we believe the error rate is less than one in a thousand,” said Carlos Bustamante, a professor of genetics at Stanford, who conducted the test.

Republicans, most famously President Donald Trump, have mocked Warren over her claims of Native American ancestry and said she used that to get preferential treatment in being hired for a teaching job at Harvard.

Warren also released an ad filmed in her native Oklahoma in which she talks about her family tree. Family lore holds that Warren’s great-great-great-grandmother was part Native American, which is consistent with the test results, according to The Boston Globe.

Watch: New Elizabeth Warren Video Reveals Genetic Test Results and Talks Heritage With Her Family

Warren had previously resisted calls to take a DNA test.

“I think this was fully litigated in 2012 here in Massachusetts,” she told a Boston public television station in March.

GOP opposition research released during her 2012 Senate run showed that when Warren was a professor at Harvard Law, a spokesman for the school cited Warren’s ancestry in order to tout the faculty’s diversity in an interview with the Harvard Crimson, the Globe reported at the time.

Warren is expected to win re-election next month in her race against Republican Geoff Diehl in a race rated Solid Democratic by Inside Elections with Nathan L. Gonzales.

Trump — who often refers to Warren as “Pocahontas” — is among those who have called for Warren to take a DNA test.

“I’m going to get one of those little kits and in the middle of the debate when she proclaims she’s of Indian heritage because her mother said she has high cheekbones,” Trump said at a Montana rally in July, the Great Falls Tribune reported.

“We will take that little kit and say — and we have to do it gently because we’re in the #MeToo generation, so we have to be very gentle — and we will very gently take that kit and we will slowly toss it, hoping it doesn’t hit her and injure her arm even though it probably only weighs two ounces. And we will say, ‘I will give you a million dollars to your favorite charity paid for by Trump if you take the test, and it shows you’re an Indian.”

Monday’s test results are Warren’s latest volley in her long-running campaign to put Trump’s taunt behind her.

Trump has frequently accused Warren of leaning on claims of Native American heritage in order to advance her career. In September, Warren released personnel records dating through her law career at University of Texas, University of Pennsylvania and Harvard University to delegitimize that allegation.

The video released Monday shows former colleagues at those schools shooting down claims that she was given preferential treatment.

In February, Warren spoke to the National Congress of American Indians. The speech coincided with her signing on to six bills on policy affecting Native American tribes, Politico reported.

“My mother’s family was part Native American. And my daddy’s parents were bitterly opposed to their relationship,” she said in the speech. “So, in 1932, when Mother was 19 and Daddy had just turned 20, they eloped.”

“The story they lived will always be a part of me. And no one — not even the president of the United States — will ever take that part of me away.”

But some Native American leaders are troubled by Warren’s use of a DNA test to claim Native heritage.

The Cherokee Nation said the test hurts the tribe’s interests in a statement Monday night.

“Using a DNA test to lay claim to any connection to the Cherokee Nation or any tribal nation, even vaguely, is inappropriate and wrong,” Cherokee Nation Secretary of State Chuck Hoskin Jr. said.

A DNA test “really doesn’t drill down to the question of whether somebody has Cherokee ancestry, for example, or ancestry of any particular tribe,” Hoskin said in an interview with CNN. “We need to be clear about what it means to be Native American, an Indian in this country. And it frankly comes down to a legal status that we have fought long and hard for and are very proud of.”

Trump’s “Pocahontas” smear echoes the “birtherism” conspiracy theory he used to discredit President Barack Obama. The conspiracy theory prompted Obama to release his long-form birth certificate in 2011. ICYMI: Warren Rebukes Trump’s ‘Pocahontas’ Nickname in Speech to National Congress of American Indians