Andrew Harnik / AP

President Donald Trump is proposing removing the right to U.S. citizenship for children born to noncitizens on U.S. soil—a move that could spark fierce debate over the Fourteenth Amendment and American identity. In a new interview with Axios, the president said he intends to revoke birthright citizenship through an executive order.

“It was always told to me that you needed a constitutional amendment. Guess what? You don’t,” Trump said in the interview, part of which aired Tuesday morning. He continued: “You can definitely do it with an act of Congress. But now they’re saying I can do it just with an executive order.”

This isn’t the first time the president has suggested he’d like to end the right. In 2015, then-candidate Trump also expressed an intent to end birthright citizenship, calling it “the biggest magnet for illegal immigration.” His stated intent takes direct aim at the Constitution and the millions of people who were born in the United States to immigrant parents.

“This is one of the longest-standing debates under the Constitution,” said Jonathan Turley, a law professor at George Washington University. The Fourteenth Amendment says that “all persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.” That clause “has proven to be maddening since it was written,” Turley said. “Various people who were involved in drafting the Fourteenth Amendment suggested that this was a condition that people be citizens or at least legal residents in the United States to be ‘subject to the jurisdiction thereof.’”

But what’s particularly tricky in this instance is the way in which Trump intends to revoke birthright citizenship: through executive order. Any attempt to do so will immediately be met with legal challenges that could end up in the Supreme Court.

The Court has had to contend with the clause before. In an 1898 case, United States v. Wong Kim Ark, the Court, citing the citizenship provision, ultimately ruled that Wong Kim Ark, the son of Chinese immigrant parents, had acquired U.S. citizenship at birth.

The historian Martha Jones, the author of Birthright Citizens: A History of Race and Rights in Antebellum America, citing Wong’s case, noted in a July Washington Post piece that “birthright has been affirmed, again and again, ensuring that no matter how racist the regime, the Constitution grants citizenship to all people born in the United States.”

The debate, Turley notes, has to do with scope—whether the clause should be interpreted to include the children of undocumented immigrants, for example, or interpreted more narrowly. With the addition of Justice Brett Kavanaugh, Trump may have an advantage on the Court should the executive order reach it, Turley said.

In the interview with Axios, Trump falsely claimed that the United States is the only nation with birthright citizenship. “We’re the only country in the world where a person comes in and has a baby, and the baby is essentially a citizen of the United States for 85 years with all of those benefits,” he said. “It’s ridiculous. It’s ridiculous. And it has to end.” NumbersUSA, a group that supports reduced immigration, has compiled a list of 33 nations that also offer birthright citizenship, including Canada, Mexico, and Brazil.

It’s not clear whether and when Trump would sign an executive order on birthright citizenship. He said in the interview that he’s discussed the matter with White House counsel, and did not provide a time frame. But it fits into a larger pattern by the administration to more narrowly consider the definition of American, and it comes amid a broader crackdown on both illegal and legal immigration.

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