Biden was afraid Trump would use Obama-esque birther attacks if he made Tammy Duckworth his VP: book

• Biden was reportedly concerned about whether Trump would attack Sen. Tammy Duckworth's birthplace.
• Duckworth pushed back hard on Biden's worries, according to a new book.

Then-presidential candidate Joe Biden and top campaign officials were afraid that President Donald Trump would weaponize the fact that Sen. Tammy Duckworth was born in Thailand if Biden selected her as his running mate, according to a forthcoming book.

Biden was reportedly concerned that Duckworth would be targeted by the same kind of racist "birther" questions that Trump and others used to attack President Barack Obama. But Duckworth pushed back.

"She reminded them that she had been attacked in racist and xenophobic terms in past campaigns, and that she had prevailed," New York Times reporters Jonathan Martin and Alex Burns wrote of Duckworth's response in "This Will Not Pass: Trump, Biden, and the Battle for America's Future," according to a Chicago Sun-Times report.

"I've beaten every a--h--- who's come after me with that," said Duckworth, an Illinois Democrat, according to the book.

Duckworth was born in Thailand in 1968 to an American father and a Thai mother of Chinese Heritage. An Iraq War veteran, Duckworth lost both of her legs during a crash. Her father was a Marine and can reportedly trace his heritage back to the Revolutionary War. Then-Republican Sen. Mark Kirk tried to question Duckworth's heritage during their heated 2016 race. He later apologized to her for bringing it up.

Only a "natural born Citizen, or a Citizen of the United States" can be president, Article II of the US Constitution lays out. The document doesn't offer a definition of a "natural born citizen," but most experts believe that having at least one American parent makes someone "natural born," NBC News reported in 2016.

Biden, of course, ended up naming Sen. Kamala Harris as his vice president. John Eastman, a conservative legal scholar who assisted Trump's efforts to overturn the election, raised a fringe theory that Harris, who was born in California, was not eligible to serve.

Two former solicitor generals of opposite parties, Paul Clement and Neal Katyal, wrote in a 2015 Harvard Law Review article that many of these questions are much ado about nothing.

"An individual born to a U.S. citizen parent — whether in California or Canada or the Canal Zone — is a U.S. citizen from birth and is fully eligible to serve as President if the people so choose," the pair wrote at the time. (Their reference to the canal zone is a nod to questions Sen. John McCain faced about his birthplace.)

The wave of 2016 stories about the question concerned Duckworth's colleague, Sen. Ted Cruz, who was born in Calgary in 1970 to an American mother and a Cuban father. Most scholars concluded at the time that Cruz would've been eligible to serve as president. Still, Trump floated questions about Cruz's birthplace, too.

"I hope he knows what he's doing, but I thought you had to be born in the country," Trump told Megyn Kelly in 2015, adding that Cruz had "one extra level of complication."

The White House and Duckworth's office did not immediately respond to Insider's requests for comment.