The question isn't natural born citizen of the US, it's the residency requirement of "fourteen Years a Resident within the United States", which everyone forgets about but which Fortuno clearly doesn't meet.
If Romney is the Republican nominee, it will be the first election between two candidates neither of whose fathers was born in the US (if you count the colonies which later became the US as "US" in the case of the early Presidents).
Before Obama, I believe that the only Presidents with foreign-born fathers were Andrew Jackson and Chester Alan Arthur (the latter was elected Vice President and only became President because of his predecessor's assassination). Woodrow Wilson's mother was born in England.