WASHINGTON — The question has nagged at the parents of Americans born outside the continental United States for generations: Dare their children aspire to grow up and become president? In the case of Senator John McCain of Arizona, the issue is becoming more than a matter of parental daydreaming.
Mr. McCain’s likely nomination as the Republican candidate for president and the happenstance of his birth in the Panama Canal Zone in 1936 are reviving a musty debate that has surfaced periodically since the founders first set quill to parchment and declared that only a “natural-born citizen” can hold the nation’s highest office.
Almost since those words were written in 1787 with scant explanation, their precise meaning has been the stuff of confusion, law school review articles, whisper campaigns and civics class debates over whether only those delivered on American soil can be truly natural born. To date, no American to take the presidential oath has had an official birthplace outside the 50 states.
“There are powerful arguments that Senator McCain or anyone else in this position is constitutionally qualified, but there is certainly no precedent,” said Sarah H. Duggin, an associate professor of law at Catholic University who has studied the issue extensively. “It is not a slam-dunk situation.”
Mr. McCain was born on a military installation in the Canal Zone, where his mother and father, a Navy officer, were stationed. His campaign advisers say they are comfortable that Mr. McCain meets the requirement and note that the question was researched for his first presidential bid in 1999 and reviewed again this time around.
But given mounting interest, the campaign recently asked Theodore B. Olson, a former solicitor general now advising Mr. McCain, to prepare a detailed legal analysis. “I don’t have much doubt about it,” said Mr. Olson, who added, though, that he still needed to finish his research.
Senator Lindsey Graham, Republican of South Carolina and one of Mr. McCain’s closest allies, said it would be incomprehensible to him if the son of a military member born in a military station could not run for president.
“He was posted there on orders from the United States government,” Mr. Graham said of Mr. McCain’s father. “If that becomes a problem, we need to tell every military family that your kid can’t be president if they take an overseas assignment.”
The phrase “natural born” was in early drafts of the Constitution. Scholars say notes of the Constitutional Convention give away little of the intent of the framers. Its origin may be traced to a letter from John Jay to George Washington, with Jay suggesting that to prevent foreigners from becoming commander in chief, the Constitution needed to “declare expressly” that only a natural-born citizen could be president.
Ms. Duggin and others who have explored the arcane subject in depth say legal argument and basic fairness may indeed be on the side of Mr. McCain, a longtime member of Congress from Arizona. But multiple experts and scholarly reviews say the issue has never been definitively resolved by either Congress or the Supreme Court.
Ms. Duggin favors a constitutional amendment to settle the matter. Others have called on Congress to guarantee that Americans born outside the national boundaries can legitimately see themselves as potential contenders for the Oval Office.
“They ought to have the same rights,” said Don Nickles, a former Republican senator from Oklahoma who in 2004 introduced legislation that would have established that children born abroad to American citizens could harbor presidential ambitions without a legal cloud over their hopes. “There is some ambiguity because there has never been a court case on what ‘natural-born citizen’ means.”
Mr. McCain’s situation is different from those of the current governors of California and Michigan, Arnold Schwarzenegger and Jennifer M. Granholm, who were born in other countries and were first citizens of those nations, rendering them naturalized Americans ineligible under current interpretations. The conflict that could conceivably ensnare Mr. McCain goes more to the interpretation of “natural born” when weighed against intent and decades of immigration law.
Mr. McCain is not the first person to find himself in these circumstances. The last Arizona Republican to be a presidential nominee, Barry Goldwater, faced the issue. He was born in the Arizona territory in 1909, three years before it became a state. But Goldwater did not win, and the view at the time was that since he was born in a continental territory that later became a state, he probably met the standard.
It also surfaced in the 1968 candidacy of George Romney, who was born in Mexico, but again was not tested. The former Connecticut politician Lowell P. Weicker Jr., born in Paris, sought a legal analysis when considering the presidency, an aide said, and was assured he was eligible. Franklin D. Roosevelt Jr. was once viewed as a potential successor to his father, but was seen by some as ineligible since he had been born on Campobello Island in Canada. The 21st president, Chester A. Arthur, whose birthplace is Vermont, was rumored to have actually been born in Canada, prompting some to question his eligibility.
Quickly recognizing confusion over the evolving nature of citizenship, the First Congress in 1790 passed a measure that did define children of citizens “born beyond the sea, or out of the limits of the United States to be natural born.” But that law is still seen as potentially unconstitutional and was overtaken by subsequent legislation that omitted the “natural-born” phrase.