Moderator Bob Schieffer, center, watches as Republican presidential candidate, former Massachusetts Gov. Mitt Romney and President Barack Obama shake hands before the start of the last debate at Lynn University, Monday, Oct. 22, 2012, in Boca Raton, Fla. (AP Photo/Pablo Martinez Monsivais)

Photo by: Pablo Martinez Monsivais

Moderator Bob Schieffer, center, watches as Republican presidential candidate, former Massachusetts Gov. Mitt Romney and President Barack Obama shake hands before the start of the last debate at Lynn University, Monday, Oct. 22, 2012, in Boca Raton, Fla. (AP Photo/Pablo Martinez Monsivais)