Shadows are cast across the floor as people pass by outside the debate hall ahead of the vice presidential debate with Republican vice presidential candidate, Rep. Paul Ryan, R-Wis., and Vice President Joe Biden, Thursday, Oct. 11, 2012, at Centre College in Danville, Ky. (AP Photo/David Goldman)
Vice President Joe Biden, left, and Republican vice presidential nominee, Rep. Paul Ryan, of Wisconsin, challenge each other during the vice presidential debate Thursday, Oct. 11, 2012, at Centre College in Danville, Ky. (AP Photo/Eric Gay)
Vice President Joe Biden and Republican vice presidential nominee Rep. Paul Ryan of Wisconsin participate in the vice presidential debate at Centre College, Thursday, Oct. 11, 2012, in Danville, Ky. (AP Photo/Pool-Rick Wilking)
Vice President Joe Biden and Republican vice presidential nominee Rep. Paul Ryan of Wisconsin participate in the vice presidential debate at Centre College, Thursday, Oct. 11, 2012, in Danville, Ky. (AP Photo/Pool-Rick Wilking)
Vice President Joe Biden and Republican vice presidential nominee Rep. Paul Ryan of Wisconsin participate in the vice presidential debate at Centre College, Thursday, Oct. 11, 2012, in Danville, Ky. (AP Photo/Pool-Rick Wilking)
A sign promoting the vice presidential debate is held up at a rally on the Centre College campus, site of the debate, Thursday, Oct. 11, 2012, in Danville, Ky. Vice President Joe Biden will face Republican vice presidential candidate, Rep. Paul Ryan, R-Wis. (AP Photo/Eric Gay)
Chris Herron of Danville, Ky., has his picture taken Oct. 11, 2012, with a cutout of President Obama outside the Norton Center on the Centre College campus in Danville, Ky., where the debate between Vice President Joe Biden and Republican vice presidential candidate Paul Ryan was to take place later that day. (Associated Press)
The corner for President Obama's campaign is seen Oct. 11, 2012, in the spin room of the media center at Centre College in Danville, Ky., ahead of the debate between Vice President Joseph R. Biden and Republican vice presidential candidate Paul Ryan. (Associated Press)
A banner made by a local middle school depicting Republican vice presidential candidate Paul Ryan and Vice President Joseph Biden hangs on the wall Oct. 10, 2012, inside the media center at Centre College in Danville, Ky. Biden and Ryan will debate at the college on Oct. 11. (Associated Press)
Republican vice presidential candidate Paul Ryan poses Oct. 10, 2012, for pictures with supporters as he arrives at the Blue Grass Airport in Lexington, Ky. (Associated Press)
Republican vice presidential candidate Paul Ryan boards the campaign jet at Clearwater International Airport in Clearwater, Fla., on Oct. 10, 2012. (Associated Press
Republican vice presidential candidate Paul Ryan speaks Oct. 10, 2012, to reporters outside Old Farmers Creamery in St. Petersburg, Fla. (Associated Press)
Students posing as Vice President Joseph R. Biden and Republican rival Rep. Paul Ryan shake hands Wednesday during setup for Thursday night’s vice presidential debate at Centre College in Danville, Ky. (Associated Press)
Supporters listen as Rep. Paul Ryan, the Republican vice presidential candidate, speaks during a campaign event at Oakland University in Rochester, Mich., on Monday, Oct. 8, 2012. (AP Photo/Mary Altaffer)
Recording artist Kid Rock speaks before introducing Republican vice presidential candidate Paul Ryan during an Oct. 8, 2012, rally at Oakland University in Rochester, Mich. (Associated Press)