Republican presidential candidate Mitt Romney, left, and his vice presidential running mate Rep. Paul Ryan, R-Wis., arrive at a campaign rally Sunday, August 12, 2012 in Mooresville, N.C. at the NASCAR Technical Institute. (AP Photo/Jason E. Miczek)

Republican presidential candidate Mitt Romney, left, and his vice presidential running mate Rep. Paul Ryan, R-Wis., arrive at a campaign rally Sunday, August 12, 2012 in Mooresville, N.C. at the NASCAR Technical Institute. (AP Photo/Jason E. Miczek)