Laurence H. Tribe, the Harvard law professor and constitutional scholar, believes the “natural born” provision has outlived its original intent considering that the redcoats are no longer coming.

“The worry that George III might come over and exert undue Germanic or British influence is no longer a threat,” said Mr. Tribe, referring to a motivating fear of the founding fathers. “There is no defense now for retaining the clause in the Constitution. It really needs to be removed.”

Before Mr. Cruz, Mr. McCain, who was born in the Panama Canal Zone, had to navigate the issue. Some have raised questions about Senator Marco Rubio, the Florida Republican and presidential candidate who was born in the United States to two Cuban immigrants who were not yet citizens. And Mr. Obama still endures questions about his citizenship despite his confirmed origins in Hawaii.

But a resolution is no easy task.

A constitutional amendment could be the most certain route. Simply excising the phrase “natural born” in a bit of constitutional copy-editing would mean that a person elected president would have to be a citizen of at least 35 years of age who has been a resident of the United States for at least 14 years — an approach that could open the presidency to naturalized citizens.

But changing the Constitution is purposefully complicated and requires overwhelming backing from Congress and state legislatures. Even well-intentioned tampering can open the door to much more explosive proposals. It is easy to imagine people would have many alternative ideas for defining the qualifications to be president once that ball got rolling.

Mr. Tribe paints a theoretical scenario where the quickest answer could be provided in a legal case. Say Mr. Cruz becomes the Republican nominee, yet is denied a spot on the ballot in a state with a meaningful number of electoral votes. As the injured party, Mr. Cruz would certainly have motivation to sue as well as standing, a threshold often difficult to meet in such cases. And the courts would have incentive to act quickly before a crisis, hopefully resulting in a definitive ruling that would settle the issue.

Perhaps the matter will never come to a head. But it is also not difficult to envision a case in which the result of the presidential election ends up in a nasty legal fight and the Supreme Court is called on to sort it out. That is not a spectacle many Americans — or members of the Supreme Court — want to see again.