Yes he is eligible!
"Romney was born to American parents in Mexico. His family moved back to the United States when he was a child."
Yes he is eligible!
"Romney was born to American parents in Mexico. His family moved back to the United States when he was a child."
George Romney was born in Mexico to American parents.
http://en.wikipedia.org/wiki/George_W._Romney
Willard Mitt Romney was born in the United States to American parents, one of whom (father George Romney) was born in Mexico to American parents.