The Constitution says that only "natural born citizens" are eligible to be president. Is Sen. Ted Cruz of Texas eligible, given that he was born in Canada of a U.S. citizen mother and a Cuban immigrant father? If Cruz runs, 2016 will be the third consecutive election in which there were questions about the right of a major party candidate to serve. Unfortunately, the Framers left few clues about exactly what a "natural born citizen" is; Congress has not used the phrase in citizenship statutes since 1790.