The all-but certain nomination of John McCain to be the Republican candidate for president has again raised a question nagging the Arizona senator: does his birth outside the United States prevent him from holding the nation's highest office?

McCain, part of a storied naval family and a Vietnam War hero in his own right, was born in 1936 on a military installation in the Panama Canal Zone. The issue of his birthplace raises the question of whether it qualifies as a foreign birth and therefore violates the constitutional requirement that a commander in chief be a "natural-born citizen."

"I have absolutely no concern about that. An American born in a territory of the United States, whose father is serving in the military, (that) could not be eligible for the presidency of the United States is certainly not something our founding fathers envisioned," McCain said aboard his plane Thursday, noting that 1964 GOP nominee Barry Goldwater was born in Arizona while it was still a territory.

South Carolina Sen. Lindsey Graham told The New York Times that it would be unthinkable for McCain -- or anyone born on a military installation -- not to be allowed to run for president.

"[McCain's father] was posted there on orders from the United States government," Graham told the Times. "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.

Click here to read more at NYTimes.com.

FOX News' Mosheh Oinounou contributed to this report.