President Barack Obama greets members of the family of Republican presidential nominee Mitt Romney after the final presidential debate at Lynn University, Oct. 22, 2012, in Boca Raton, Fla.

U.S. President Barack Obama speaks at the final presidential debate at Lynn University in Boca Raton, Fla, Oct. 22, 2012.

Republican presidential nominee Mitt Romney makes a point during the final presidential debate with President Barack Obama at Lynn University, Oct. 22, 2012, in Boca Raton, Fla.

President Barack Obama speaks during the third presidential debate with Republican presidential nominee Mitt Romney at Lynn University, Oct. 22, 2012, in Boca Raton, Fla.

Republican presidential candidate Mitt Romney speaks during his final debate with President Barack Obama at the Keith C. and Elaine Johnson Wold Performing Arts Center at Lynn University, Oct. 22, 2012, in Boca Raton, Fla.

President Obama speaks during the second presidential debate Oct. 16, 2012, at Hofstra University in Hempstead, N.Y.

Republican presidential nominee Mitt Romney speaks on Oct. 16, 2012, during the second of three presidential debates at Hofstra University in Hempstead, N.Y.

Vice President Joe Biden and Republican vice presidential nominee Rep. Paul Ryan of Wisconsin react during the vice presidential debate at Centre College, Oct. 11, 2012, in Danville, Ky.

Republican vice presidential nominee Rep. Paul Ryan of Wisconsin, right, watches as Vice President Joe Biden speaks during the vice presidential debate at Centre College, Oct. 11, 2012, in Danville, Ky.

Vice President Joe Biden, left, and Republican vice presidential nominee Rep. Paul Ryan of Wisconsin answer a question during the vice presidential debate at Centre College, Oct. 11, 2012, in Danville, Ky.

Vice President Joe Biden and Republican vice presidential nominee Rep. Paul Ryan of Wisconsin participate in the vice presidential debate at Centre College, Oct. 11, 2012, in Danville, Ky.

Vice President Joe Biden answers a question during the vice presidential debate at Centre College, Oct. 11, 2012, in Danville, Ky.

Republican vice presidential nominee, Rep. Paul Ryan of Wisconsin, makes a point during the vice presidential debate with Vice President Joe Biden at Centre College, Oct. 11, 2012, in Danville, Ky.

Republican presidential nominee Mitt Romney answers a question during the first presidential debate at the University of Denver, Oct. 3, 2012, in Denver.

President Barack Obama listens during his debate with Republican Presidential candidate Mitt Romney at the University of Denver in Denver, Colorado, Oct. 3, 2012.

Republican presidential candidate Mitt Romney listens during the Presidential Debate at the University of Denver, Oct. 3, 2012 in Denver.

US President Barack Obama listens during his debate with Republican presidential candidate Mitt Romney at Magness Arena at the University of Denver in Denver, Oct. 3, 2012.

President Barack Obama speaks during his debate with Republican presidential nominee Mitt Romney at the University of Denver in Denver, Oct. 3, 2012.

Republican presidential nominee Mitt Romney speaks during the presidential debate at the University of Denver, Oct. 3, 2012 in Denver.

President Barack Obama listens during his debate with Republican presidential candidate Mitt Romney at Magness Arena at the University of Denver in Denver, Oct. 3, 2012.

Republican presidential nominee Mitt Romney speaks during the presidential debate at the University of Denver, Oct. 3, 2012 in Denver.

The Republican presidential nominee, Mitt Romney, shakes hands with the Democratic presidential candidate, President Barack Obama, during the presidential debate at the University of Denver, Oct. 3, 2012 in Denver.

President Barack Obama shakes hands with Republican presidential candidate Mitt Romney, Oct. 3, 2012 in Denver, at the start of the first of three presidential debates.