‘He was born in Miami. How is that not natural born?’
Allow me to answer -
Natural born citizen is citizenship by nature, i.e. by place of birth AND by parentage - born on US soil to 2 USA citizen parentS.
A natural born citizen has undivided loyalty to USA.
Marco Rubio was born to a father who was not a USA citizen at time of Rubio’s birth. His father was a Cuban citizen at time of Marco’s birth, therefore Marco has dual citizenship - Cuban and USA (if he indeed is a USA citizen due only to his birth in USA)
Who’s says so? Constitution says no such thing.