Sen. Elizabeth Warren (D-Mass.) has released a DNA test that suggests she has a distant Native American ancestor — a move that set off a fresh round of barbs Monday between the likely 2020 presidential contender and the current occupant of the Oval Office.

A report distributed by Warren concludes that there is “strong evidence” that the senator had a Native American in her family tree dating back six to 10 generations, part of an extraordinary effort to discredit President Trump and others who have questioned her claims about her heritage.

The test results, after first being reported by the Boston Globe, were widely distributed to reporters Monday morning by Warren’s Senate campaign committee, along with a video on her upbringing and a link to a new “fact squad” website that seeks to debunk her critics.

The DNA analysis, by Carlos D. Bustamante, a Stanford University professor, concludes that “the vast majority” of Warren’s ancestry is European but that “the results strongly support the existence of an unadmixed Native American ancestor in the individual’s pedigree, likely in the range of 6-10 generations ago.”

Speaking to reporters Monday morning as he left the White House, Trump’s initial reaction to the DNA report was: “Who cares?”

“I hope she’s running for president because I think she’d be very easy,” he added. “I hope that she’s running. I do not think that she’d be difficult at all. She’ll destroy the country. She’ll make our country into Venezuela. With that being said, I don’t want to say bad things about her, because I hope she would be one of the people that would get through the process.”

Later, when asked whether he plans to honor a pledge he made in July to make a $1 million donation if Warren took a DNA test “and it shows you’re an Indian,” Trump laid out a new condition.

“I’ll only do it if I can test her personally,” Trump said during an exchange with reporters at an American Red Cross building in Macon, Ga., where he was touring areas hit by Hurricane Michael.

He added that testing Warren would “not be something I will enjoy doing, either.” It was not immediately clear what Trump meant by the comment.

Trump went on to mock Warren, saying that she “owes the country an apology.”

“How much? 1/1000th?” he said when asked about the DNA test results.

Trump has frequently mocked Warren’s claims about her heritage, calling her “Pocahontas.” During a freewheeling phone interview with Fox News last week, he asserted that the senator “faked her heritage,” adding: “I have more Indian blood in me than her, and I have none.”

In a tweet Monday morning, Warren reminded Trump of his promise to make a donation and chose a charity.

“Please send the check to the National Indigenous Women’s Resource Center,” she wrote, describing the organization as “a nonprofit working to protect Native women from violence.”

Asked about his pledge Monday, Trump denied to reporters having made it.

“I didn’t say that. You better read it again,” Trump said as he left the White House en route to Florida to view hurricane damage.

At the July rally, Trump said, “I’m going to get one of those little [DNA testing] kits and in the middle of the [presidential] debate, when she proclaims she’s of Indian heritage.

“And we will say, ‘I will give you a million dollars, paid for by Trump, to your favorite charity, if you take the test and it shows you’re an Indian.’ And we’ll see what she does. I have a feeling she will say no, but we will hold it for the debates.”

After Trump spoke to reporters, Warren tweeted: “Having some memory problems, @realDonaldTrump? Should we call for a doctor?”

That timing in Bustamante’s DNA report fits Warren’s family lore, passed down during her Oklahoma upbringing, that her great-great-great-grandmother, O.C. Sarah Smith, was at least partially Native American, the Globe reported.

But the Republican National Committee seized on the report, suggesting that it did little to bolster her contention. The RNC pointed out that if Warren’s Native American ancestor was from 10 generations ago, that would make her less than 0.1 percent Native American.

“To put that in perspective, Warren might even be less Native American than the average European American,” the RNC said, pointing to a 2014 study published in the American Journal of Human Genetics that found that “European-Americans had genomes that were on average 98.6 percent European, .19 percent African, and .18 Native American.”

The video distributed by Warren’s campaign begins with Trump’s comments and features several of her relatives in Oklahoma, including some Republicans, saying they find them offensive.

Warren then narrates her family history.

“My mother was born in eastern Oklahoma,” she says. “It had been Indian territory until just a few years earlier, when it had become a state. My daddy always said he fell head over heels in love with my mother the first time he saw her.”

But she recounts that her father’s parents were “bitterly opposed” to a marriage because her mother’s family was partly Native American. So the couple eloped, she says.

The nearly six-minute video also tackles claims that Warren represented herself as a minority to advance as a law professor, a notion that White House press secretary Sarah Huckabee Sanders, among others, have advanced.

The video shows Sanders making that claim from the White House briefing room and then shows interviews with several law professors who deny that Warren’s Native American heritage played a role in her hiring or advancement. Her colleagues also tout Warren’s skills as a teacher.

Bustamante, a genetics professor, is also featured in the video, which closes with Warren taking aim at Trump, saying: “Trump can say whatever he wants about me, but mocking Native Americans or any group to try to get at me, that’s not what America stands for.”

Later Monday morning on Twitter, Warren continued to goad Trump,

“I took this test and released the results for anyone who cares to see because I’ve got nothing to hide,” she wrote. “What are YOU hiding, @realDonaldTrump? Release your tax returns — or the Democratic-led House will do it for you soon enough. Tick-tock, Mr President.”

Warren previously cited family stories to claim Cherokee and Delaware Indian heritage, and her background has been publicly questioned since at least 2012.

In a February speech to the National Congress of American Indians, Warren rebuked Trump’s persistent mockery of her as “Pocahontas” and spoke in detail about her family’s history.

In August, she made her personnel files available to the Boston Globe, showing that ethnicity was not a factor in her rise as a law professor.

Warren has been building an expansive shadow war room designed to help elect Democrats across the country in next month’s midterm elections and bolster her presence in key states that hold 2020 nominating contests.

She has deployed staffers to all four early primary or caucus states — two to New Hampshire and one each to Iowa, South Carolina and Nevada — as well as to traditional powerhouses such as Ohio, Florida, Michigan and Wisconsin.

Warren is seeking reelection herself in Massachusetts next month and is expected to easily win a second Senate term.

She has said she will “take a hard look”at running for president after the midterms.

Matt Viser, Felicia Sonmez and Amy B Wang contributed to this report.