(WASHINGTON) — President Donald Trump on Thursday promoted a false and racist theory that Sen. Kamala Harris, the first woman of color on a major political party general election ticket — who was born in California — is not eligible to be vice president because her two parents were immigrants.

At a White House briefing, Trump amplified the baseless theory that had gained traction in some right-wing circles since Harris was announced as Joe Biden’s running mate on Tuesday, including being embraced by his own reelection campaign legal adviser.

Despite Trump and his allies pushing the claims about Harris, experts say the false theory has absolutely no basis in the U.S. Constitution, and Harris, born in Oakland in 1964, is a U.S. citizen eligible to serve as president or vice president.

“I heard it today that she doesn’t meet the requirements,” the president said when asked by a reporter, while also boosting the credentials of the author of widely panned op-ed highlighting the theory as a “very highly qualified, very talented lawyer.”

“I have no idea if that’s right, I would’ve — I would have assumed the Democrats would have checked that out before she gets chosen to run for vice president. That’s very serious,” the president said, echoing previous racist attacks the president made on former President Barack Obama, falsely questioning his birth certificate and the legitimacy of the first Black United States president.

Kate Shaw, a professor at the Cardozo School of Law and an ABC News Supreme Court contributor, said it’s an “absolutely baseless argument,” and said the concerns don’t compare to questions raised in the 2016 campaign about Texas GOP Sen. Ted Cruz.

“She was born here and has lived her whole life here; she’s a natural born citizen, eligible, full stop. The questions around the eligibility of Ted Cruz, who was born in Canada, were legitimate ones, though I thought he was eligible. These aren’t.”

Sheldon Goldman, Distinguished Professor of Political Science Meritus at the University of Massachusetts at Amherst, called the argument being made about Harris’ eligibility “100 percent bogus.”

“The 14th Amendment provides a clear definition of citizenship. Anyone born in the United States is an American citizen regardless of where their parents were born,” Goldman told ABC News.

The Biden/Harris campaign quickly condemned the false theory, and Trump for giving it oxygen at Thursday’s briefing, pointing to his history of spreading a similar false and racist theory about his predecessor.

“Donald Trump was the national leader of the grotesque, racist birther movement with respect to President Obama and has sought to fuel racism and tear our nation apart on every single day of his presidency,” Biden spokesperson Andrew Bates said in a statement to ABC News. “So it’s unsurprising, but no less abhorrent, that as Trump makes a fool of himself straining to distract the American people from the horrific toll of his failed coronavirus response that his campaign and their allies would resort to wretched, demonstrably false lies in their pathetic desperation.”

Before Trump pushed the false theory questioning Harris’ citizenship, it gained traction after a widely panned Newsweek op-ed by conservative law professor John C. Eastman, who argued that Harris might not be a “natural born citizen” despite being born in California because Harris’ parents weren’t naturalized citizens at the time at the time she was born.

But Bernadette Meyle, Carl and Sheila Spaeth Professor of Law at Stanford Law School, told ABC News that argument has “no basis in constitutional law,” saying it’s been settled law since the Supreme Court decided the issue in 1898.

“The language of the Fourteenth Amendment stating “subject to the jurisdiction thereof” was debated for a period following the Amendment, where some claimed that this phrase meant to incorporate descent and parents’ citizenship into the Amendment in terms of considering whether someone should be considered a citizen by birth…however, Trump in his 2016 campaign tried to make the argument that the Newsweek article is making, then later seemed to drop it. It has been a claim brought up several times by right-wing thinkers over the past decade or so. It has, however, no basis in constitutional law.”

Trump campaign legal adviser Jenna Ellis shared the op-ed on Twitter on Tuesday morning and later, when asked about pushing the false theory herself, told ABC News: “It’s an open question, and one I think [Sen. Kamala D.] Harris should answer so the American people know for sure she is eligible.”

The Trump campaign did not respond to ABC News requests for comment on Ellis’ statement.

On Friday, Jared Kushner, Trump’s son-in-law and senior adviser, told CBS News: “At the end of the day, it’s something that’s out there” before saying, “I personally have no reason to believe she’s not,” referring to Harris’ eligibility.

Trump now encouraging questions over Harris’s citizenship echoes how he rose to political prominence, in part, by making false allegations about Obama’s birth certificate as part of the “birther” conspiracy movement.

In recent years, however, Trump has attempted to publicly distance himself from the false birther theory he had long-championed. In September 2016, then-Republican presidential nominee Trump acknowledged for the first time — five years after the former president released his long-form birth certificate — that Obama was born in the United States.

Still, in late 2017 the president continued to question its authenticity behind closed doors, according to The New York Times.

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