2012 vice presidential debate

Vice President Joe Biden and Republican candidate Paul D. Ryan trade jabs at their debate as Martha Raddatz moderates.  (Chip Somodevilla / Getty Images)

Republican vice presidential candidate Paul D. Ryan of Wisconsin makes a point at the debate.  (Chip Somodevilla / Getty Images)

Vice President Joe Biden and Republican vice presidential candidate Paul D. Ryan shake hands before the debate.  (Win McNamee / Getty Images)

A sign welcomes visitors to the vice presidential debate at Centre College in Danville, Ky.  (Nicholas Kamm/AFP/Getty Images)

A storefront window in downtown Danville, Ky., promotes the vice presidential debate.   (Chip Somodevilla/Getty Images)

Students walk past a political mural near Centre College in downtown Danville, Ky.   (Chip Somodevilla/Getty Images)

Sam Adams of Lexington stages a one-man demonstration against the Democratic presidential ticket in Danville, Ky., site of the vice presidential debate.   (Chip Somodevilla/Getty Images)

Obama campaign items are sold in Danville, Ky., before the vice presidential debate.   (Nicholas Kamm / AFP/Getty Images)

Abraham Lincoln impersonator Larry Elliott of Louisville poses with cutouts of the presidential candidates in Danville, Ky., site of the vice presidential debate.   (Charlie Neibergall/Associated Press)