This image released by CBS News Sunday, Jan. 8, 2012, shows Sen. John McCain, R-Ariz., on "Face the Nation" in Washington. McCain discussed his endorsement of Mitt Romney and the 2012 presidential campaign. (AP Photo/CBS News, Chris Usher)

This image released by CBS News Sunday, Jan. 8, 2012, shows Sen. John McCain, R-Ariz., on "Face the Nation" in Washington. McCain discussed his endorsement of Mitt Romney and the 2012 presidential campaign. (AP Photo/CBS News, Chris Usher)