However, the precise definition of "natural-born Citizen" as it appears in the Constitution has been debatable. If it turns out that BO was born in Kenya, I would be certain that he would not be considered a "natural-born Citizen" by any objective logic. But if he was born in Hawaii - as he has always claimed yet never documented - he would have a stronger argument to claim "natural-born Citizen" status.
It is very defined which is the whole problem for Obama and the reason he has been so tight lipped about it.
Its all here if you wish to learn about it.
http://www.theobamafile.com/ObamaLatest.htm