This chart published by the Obama File attempts to clarify the differences between a citizen, a native-born citizen, and a natural-born citizen.
His site explained: "Obama is not a 'natural born citizen' because his father was a Kenyan national and a British subject. To be a natural born citizen, a person's parents must BOTH be citizens of the United States of America. Further, that person must be born in the United States."
Parker Shannon of the Obama File highlighted excerpts from the 1st U.S. Congress in his effort to demonstrate a natural born citizen must be the child of two U.S. citizens.