Republican presidential candidate and former Massachusetts Gov. Mitt Romney addresses an audience March 18, 2012, during a campaign stop in Vernon Hills, Ill., as his wife, Ann, looks on. (Associated Press)

Photo by: Steven Senne

Republican presidential candidate and former Massachusetts Gov. Mitt Romney addresses an audience March 18, 2012, during a campaign stop in Vernon Hills, Ill., as his wife, Ann, looks on. (Associated Press)