House GOP conference chair Liz Cheney, R-Wyo., on Sunday suggested that 2020 presidential contender Elizabeth Warren should be disbarred for falsely claiming American Indian heritage on a recently unearthed form she submitted to the Texas State Bar in 1986.

Warren, the Massachusetts Democratic senator who formally launched her bid for the White House on Saturday, has apologized privately for identifying as a Native American "for almost two decades." Nevertheless, Warren's attempts to defuse the ensuing bipartisan criticism -- including her decision to take a DNA test last year -- have largely backfired, and highlighted what President Trump has called Warren's fatal political vulnerability.

On Saturday, Trump again derided Warren for falsely claiming Native American ancestry in what he says was a cynical effort to boost her career as a law professor by taking advantage of affirmative action. Calling Warren "Pocahontas," Trump told Warren, "See you on the campaign TRAIL." (Back in Iowa on Sunday as a full-fledged presidential candidate, Warren returned fire, say Trump "may not even be a free person" by next year's election.)

Asked by anchor Jake Tapper to respond to Trump's rhetoric, Cheney said Warren deserved the ridicule.

"Look, Elizabeth Warren has made herself a laughingstock. I don't think anybody should be surprised that that's been the reaction to her," Cheney said on CNN's "State of the Union."

The April 1986 bar card, initially reported by The Washington Post, is the first known instance of Warren claiming Native American ancestry in an official document or in her own handwriting. Warren was a professor at the University of Texas School of Law when she filled it out.

"One wonders whether or not that's grounds for disbarment, if you misrepresent yourself on your application to the bar. I'd say it probably is grounds for disbarment," Cheney said.

Under the Texas Rules of Professional Conduct, applicants are obligated to correct any material false statements they make to the State Bar during their application process -- and even if they are admitted to the bar, past misstatements that surface can still be grounds for disbarment or suspension from the practice of law. (State bars, which regulate attorney conduct and enforce discipline, are distinct from more informal -- and more numerous -- bar associations.)

Still, it remained highly unlikely that an ethics investigation would be initiated against Warren, due to the length of time that has transpired since her allegation and the difficulty in proving that she knew her statement was false.

The Texas State Bar document, which functions as a kind of directory entry for lawyers, is among multiple instances in which Warren described herself as a Native American. For example, Warren had indicated that she was Cherokee in an Oklahoma cookbook called " Pow Wow Chow" in 1984, and listed herself as a minority in the Association of American Law Schools Directory of Faculty from 1986 to 1995 -- a move she said later was an effort to "connect" with other “people like me."

Warren dropped off the list in 1995, after moving to Harvard Law School. But in 1996, an article in the student-run Harvard Crimson apparently indicated that faculty members and administrators still believed Warren was Native American.

A 2005 document obtained by The Hill, meanwhile, indicated that the University of Pennsylvania Law School considered Warren among its past minority faculty members. Warren, who had resigned by the time the university published that document, taught at the law school in the 1980s and 1990s before taking a professorship at Harvard.

"The notion that anybody of any political party would pretend that they were a member of a tribe or pretend they were Native American and would do it as she seems to have done it in order to get benefits, that is, in my view, the disgrace," Cheney added.

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Past reporting by several outlets, including CNN, held that Warren "had not" listed herself as a minority in her "student applications and during her time as a teacher at the University of Texas." Records unearthed by The Boston Globe found that in 1981, 1985, and 1988, personnel forms at the University of Texas showed that Warren had called herself "white."

Through it all, Warren has maintained that she did not use her claims of ancestry to advance her academic career. An extensive investigation by the Globe did not support the contention that Harvard had relied on Warren's' claims of Native American heritage in deciding whether to hire her.

Randall Kennedy, a law professor in charge of recruiting minority candidates at Harvard at the time, told the Globe that Warren was never considered a minority for hiring purposes.

“She was not on the radar screen at all in terms of a racial minority hire,” Kennedy said. “It was just not an issue. I can’t remember anybody ever mentioning her in this context."

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Warren's prospective presidential candidacy has had a rocky start since she announced that she had formed an exploratory committee for a White House bid on Dec. 31. That evening, Warren was widely mocked for appearing in an Instagram live feed and awkwardly telling the audience, "Hold on a second -- I'm gonna get me a beer."

Warren's' husband later walked into the kitchen, prompting Warren to tell him, "Thank you for being here." He replied, matter-of-factly: "Enjoy your beer."

Trump later savaged the episode as "the Elizabeth Warren beer catastrophe."

On Tuesday, filings revealed that Warren is worth more than $4 million -- complicating her effort to appeal to working-class voters with proposals like an unprecedented tax on wealth. in January, Warren proposed an unprecedented tax of 2 percent annually on all assets belonging to households worth more than $50 million, as well as a 1 percent tax on households with $1 billion or more.

Critics have charged that the idea is both dangerous and unconstitutional because it directly taxes wealth that is not transferred, invested, or earned as income, without ensuring the tax is evenly distributed across states.

And over the weekend, Harry Reid, the longtime Democrat who represented Nevada in the Senate for three decades and served as the Senate majority leader for eight years, declined to endorse Warren's nascent presidential run.

Although he called Warren a "good person" in an interview with The Boston Globe, Reid, 79, asserted that "my Nevada politics keep me from publicly endorsing her." He added that "anything I can do to help Elizabeth Warren short of the endorsement, I will do.”

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Reid helped catapult Warren into the national spotlight by appointing her in November 2008 to the Congressional Oversight Panel, a five-member committee responsible for overseeing the federal bailout provided by the Emergency Economic Stabilization Act.

Fox News' Andrew O'Reilly and The Associated Press contributed to this report.