HOUSTON -- Republican presidential candidate Herman Cain said Thursday that he would definitely consider an invitation to run as the eventual nominee’s vice president, except if the nominee turns out to be Texas Gov. Rick Perry. Cain, who rocketed to the top tier of the GOP field in several recent polls, was asked by reporters on the campaign trail for his thoughts on a hypothetical invitation to run as the eventual nominee’s No. 2. After offering the obligatory comment that he intends to be the nominee, Cain said, “Quite frankly, based upon Gov. Perry’s position on some issues, I would...