Laurence Tribe, a professor at Harvard Law School, told ABC News that Trump’s alternative definition would mean that only citizens born in the United States would be eligible.

“My own view as a constitutional scholar is that the better view — the one most consistent with the entire Constitution — is the broader definition, according to which Cruz would be eligible,” he said, including anyone who is a U.S. citizen at birth and doesn’t need to be naturalized.

Burt Neuborne, a professor at New York University Law School, agreed: “It seems to me that his citizenship is just as good as Donald Trump’s citizenship.”

Facing questions about his nationality before he announced his candidacy for president, Cruz took the unusual step in June 2014 of formally renouncing his Canadian citizenship. Cruz said today on the campaign trail that the question is “settled law.” But most scholars agree that the question has not yet been officially resolved.

“I think there’s a scholarly consensus, but it’s not a done deal,” said Sarah Helene Duggin, a professor at the Catholic University of America, adding that experts aren’t unanimous on the issue. “I don’t think it’s open and shut at all.”