As liberals and conservatives alike call for Sen. Elizabeth Warren to test her DNA for Native American heritage, one man has already tried.

Six years ago, conservative Boston radio host Howie Carr obtained the cap of a pen Warren chewed on at a book signing and submitted it to a lab for testing.

“Alas, there wasn’t enough saliva on it,” he wrote in a Boston Herald op-ed Friday describing the 2012 sting.

Carr’s revelation comes amid a growing chorus of both conservative and liberal voices imploring Warren — who grew up in Oklahoma and has claimed she is part Native American — to put the matter to rest by getting a DNA test and publishing the results.

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Warren has been defiant about the questions lingering around her ancestry.

“I think this was fully litigated in 2012 here in Massachusetts,” she told public television station WGBY in an interview earlier this month.

“The way I see it, at the end of the day what the people of Massachusetts said is they care a whole lot more about their families than they did about my background,” she said. “My brothers and I, we grew up in Oklahoma, and we know our story from our mom and our dad and our grandmothers and our grandfather.”

President Donald Trump gave her the nickname “Pocahontas” and has accused Warren of claiming Native American ancestry to game affirmative action protocols and increase her odds of landing top professorial jobs at the University of Pennsylvania and Harvard University, where she most recently taught.

Warren has said she self-identified as Native American after she had been hired at both of the universities.

Warren’s claims rest on stories from her parents about her mother’s native ancestry.

“My mother’s family was part Native American. And my daddy’s parents were bitterly opposed to their relationship,” she told an audience at the National Congress of American Indians in February. “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.”

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Correction 1:40 p.m. | An earlier version of this story mischaracterized when Warren identified as Native American at Harvard and Penn.