FILE - In this Oct. 24, 2012 file photo, Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks as he campaigns at Landmark Aviation at The Eastern Iowa Airport

 

              FILE - In this Oct. 24, 2012 file photo, Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks as he campaigns at Landmark Aviation at The Eastern Iowa Airport
FILE - In this Oct. 24, 2012 file photo, Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks as he campaigns at Landmark Aviation at The Eastern Iowa Airport in Cedar Rapids, Iowa. Romney and President Barack Obama are on guard for anything that could tip a presidential race that polls show is close. An autumn surprise is just that, making most late-breaking events tough to plan for. (AP Photo/Charles Dharapak, File)