In a report based on an interview with Axios set to air on its new show, "Axios on HBO," the organization's reporter said such an order would be "the most dramatic move yet" in Trump's crackdown on illegal immigration, targeting so-called "anchor babies." It will almost certainly set off another stand-off with the courts, as Trump's authority to impose such a change via executive order is up for debate.

Trump said in an interview that he has run the idea of ending birthright citizenship by his counsel and plans to proceed with the highly controversial move, which certainly will face legal challenges.

"It was always told to me that you needed a constitutional amendment. Guess what? You don't," Trump said, declaring he can do it by executive order.

When told says that's very much in dispute, Trump replied: "You can definitely do it with an Act of Congress. But now they're saying I can do it just with an executive order."

"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 ... with all of those benefits," Trump continued. "It's ridiculous. It's ridiculous. And it has to end."

"It's in the process. It'll happen ... with an executive order."

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Trump said he was surprised that Axios had caught wind of his plan.

"I didn't think anybody knew that but me. I thought I was the only one. "

Axios later clarified that it had been working to confirm the story for weeks before the interview.

While any attempt to remove birthright citizenship would undoubtedly set off a constitutional challenge...

"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."