Anyone know to whom this refers?
McCain, for one.
George Romney, who ran for the Republican party nomination in 1968, was born in Mexico to U.S. parents.
Barry Goldwater, who ran as the Republican party nominee in 1964, was born in Arizona while it was still a U.S. territory. However, although Arizona was not a state, it was a fully organized and incorporated territory of the United States.
Lowell Weicker, the former Connecticut Senator, Representative, and Governor, entered the race for the Republican party nomination of 1980 but dropped out before voting in the primaries began. He was born in Paris, France.
John McCain, who ran for the Republican party nomination in 2000 and was the Republican nominee in 2008, was born at the Coco Solo U.S. military base in the Panama Canal Zone to U.S. parents.
http://en.wikipedia.org/wiki/Natural-born_citizen#US_presidential_candidates_born_outside_the_US
Can't vouch for this website, but here's a start:
US Presidential candidates born outside the US
Barry Goldwater
George Romney
Lowell Weicker
John McCain