

A US Secret Service Agent stands at detail behind Republican presidential nominee Mitt Romney as he speaks during a campaign rally at the Golden Lamb in Lebanon, Ohio October 13, 2012. Shannon Stapleton/Reuters
US President Barack Obama gestures while speaking at an Obama Victory Fund concert while at the Bill Graham Civic Auditorium in San Francisco October 8, 2012. Larry Downing/Reuters
A silhouetted President Barack Obama gestures while speaking at a campaign event at Delray Beach Tennis Center, Tuesday, Oct. 23, 2012 in Delray Beach, Fla. Pablo Martinez Monsivais/AP
Republican presidential nominee Mitt Romney speaks during a campaign rally in a downpour in Newport News, Virginia October 8, 2012. Shannon Stapleton/Reuters
Supporters of US Republican presidential nominee and former Massachusetts Governor Mitt Romney cheer at a campaign rally in Daytona Beach, Florida, October 19, 2012. Jim Young/Reuters
Ethel Bryant, a supporter of US President Barack Obama, wears a t-shirt featuring an image of Obama as a boxer during a campaign rally at Cornell College in Mt Vernon, Iowa, October 17, 2012. Jason Reed/Reuters
US Republican presidential nominee and former Massachusetts Governor Mitt Romney arrives at a campaign rally in Chesapeake, Virginia, October 17, 2012. Jim Young/Reuters
President Barack Obama speaks at a campaign event at City Park in Denver, Wednesday, Oct. 24, 2012. Pablo Martinez Monsivais/AP
President Obama speaks at a campaign event at Lions Park, Thursday, Sept. 13, 2012, in Golden, Colo. Carolyn Kaster/AP
Mitt Romney and his wife, Ann, walk past rolls of sheet metal as they arrive at a campaign rally at American Posts in Toledo, Ohio, Feb. 29, 2012. Gerald Herbert/AP
Journalists watch the first 2012 Presidential Debate at the University of Denver, Wednesday, Oct. 3, 2012. Helen H. Richardson/The Denver Post/AP
Former Gov. Mitt Romney of Massachusetts speaks to cadets and supporters at a campaign stop at Valley Forge Military Academy in Wayne, Pa., on Sept. 28, 2012. Brian Snyder/Reuters
Mitt Romney is reflected on the side of his vehicle as he leaves The Church of Jesus Christ of Latter Day Saints in Wolfeboro, N.H., Sept. 2, 2012. Brian Snyder/Reuters
Chris Dalrymple sells T-shirts as people stream into the Farm Bureau Live amphitheater to hear President Obama speak at a campaign stop in Virginia Beach, Va., Sept. 27, 2012. Preston Gannaway/The Virginian-Pilot/AP
Mitt Romney is reflected in the teleprompter at the Ross County Court House, Aug. 14, 2012 in Chillicothe, Ohio. Mary Altaffer/AP
Mitt Romney talks with his body man Garrett Jackson after getting off his plane for a campaign event at Watson Truck and Supply, Aug. 23, 2012, in Hobbs, N.M. Evan Vucci/AP