Republican presidential contender Mitt Romney campaigning in Ames, Iowa, on Thursday (Dec. 29, 2011). Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images

Gen. David Petraeus in Kandahar, Afghanistan, on July 4, 2011. U.S. Navy Lt. j.g. Haraz N. Ghanbari/Getty Images hide caption

itoggle caption U.S. Navy Lt. j.g. Haraz N. Ghanbari/Getty Images