Republican presidential nominee Mitt Romney, left, and President Barack Obama spar during a presidential debate at Hofstra University in Hempstead, New York, Oct. 16, 2012.
Republican presidential candidate John McCain (L) and Democratic presidential candidate Barack Obama (R) take part in their first 2008 presidential debate at the University of Mississippi in Oxford, Mississippi, Sept. 26, 2008.
Democratic presidential candidate Sen. John Kerry answers a question as President Bush listens during the presidential debate in Tempe, Arizona, Oct. 13, 2004.
Moderator Jim Lehrer tells Republican presidential candidate Texas Gov. George W. Bush, right, that the candidates made the rules as Democratic presidential candidate Vice President Al Gore listens at the first presidential debate, Oct. 3, 2000, at the Clark Athletic Center on the campus of the University of Massachusetts in Boston.