Why is Rubio NOT a natural born citizen?
There is a school of thought that holds one’s parents must be citizens at the time of one’s birth to qualify as a NBC. Best I can determine, those who subscribe to this definition are in the minority.
Rubio’s parents were not citizens at the time of his birth. Rubio is a native born citizen, not a natural born citizen.
His parents were foreigners, and the child must have both parents be Americans at the time of his birth.