Trump told “Axios on HBO” for an episode set to air Nov. 4 that he has run the idea of ending birthright citizenship by his counsel and he plans to proceed with an executive order, which is sure to face legal challenges.

“It was always told to me that you needed a constitutional amendment. Guess what? You don’t,” Trump said. “You can definitely do it with an Act of Congress. But now they’re saying I can do it just with an executive order.”

Anyone born in the United States automatically has the right to U.S. citizenship, as per the 14th Amendment, which states: “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.” Trump’s stance on immigration during his campaign included abolishing birthright citizenship, which he said is “a magnet for illegal immigration.”

“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 told Axios. “It’s ridiculous. It’s ridiculous. And it has to end.”

CNN points out that Canada and a few dozen other countries also have policies of birthright citizenship.

Is it likely? Michael Anton, a former national security official in the Trump administration, said in the Washington Post that an executive order would suffice to end birthright citizenship. An executive order changing birthright citizenship would bring about a lawsuit sure to make it to the Supreme Court, Vox reports. Then the Supreme Court, now with a full bench, would decide whether it was willing to tell the president he was overstepping his bounds.

Some conservatives have argued that the 14th Amendment was only intended to provide citizenship to children born in the U.S. to lawful permanent residents — not to unauthorized immigrants or those on temporary visas. Rep. Steve King of Iowa has repeatedly introduced bills in Congress aiming to end birthright citizenship, proposing that it only be allowed if at least one parent is a U.S. citizen, lawful permanent resident or immigrant in active service in the U.S. armed forces.

Meanwhile, Trump has ordered 5,200 active-duty troops be sent to the U.S. border with Mexico to respond to a caravan of Central American migrants that Trump called an “invasion of our country.” The migrants, whose numbers have dropped from 7,000 to 3,500, are still weeks away from the border, if they arrive at all. Many are fleeing violence in Central America and are expected to apply for asylum in the U.S.

On a related note, First Lady Melania Trump’s Slovenian parents were naturalized as U.S. citizens in August. The method of acquiring this permanent status through family sponsorship is the same process Trump has repeatedly criticized as “chain migration.”