Rubio is an American. But he can't ever be the POTUS since he's not natural born. His parents were CUBAN when he was born.
>>Now, consider Marco Rubio. His parents were resident aliens when he was born in 1971, seeking and soon to receive their status as naturalized U.S. citizens. Under the Fourteenth Amendment, “all persons born...in the United States and subject to the jurisdiction thereof, are citizens of the United States and of the states wherein they reside.” This “subject to the jurisdiction thereof” clause shows why Rubio is — and, very likely, why children of illegal aliens are not — a “natural born citizen of the United States.”<<
http://www.americanthinker.com/2011/07/the_good_news_rubios_eligible.html#ixzz2JxK8gJhp