Republican presidential candidates former Massachusetts Gov. Mitt Romney, left, and Texas Gov. Rick Perry answer a question during a Republican presidential candidate debate at the Reagan Library Wednesday, Sept. 7, 2011, in Simi Valley, Calif. (AP Photo/Jae C. Hong)
Texas Gov. Rick Perry arrives for a Republican presidential debate at the Ronald Reagan Library in Simi Valley, Calif., on Wednesday. Mr. Perry introduced himself to a national audience and appeared with his GOP rivals on the same stage for the first time since entering the race last month.
Sen. Marco Rubio (right), Florida Republican, helps former first lady Nancy Reagan as she takes a tumble at the Reagan Forum at the Ronald Reagan Presidential Library and Museum in Simi Valley, Calif., on Tuesday, Aug. 23, 2011. (AP Photo/Jae C. Hong)