US presidential candidates (L-R) former Arkansas Governor Mike Huckabee, US Rep. Ron Paul (R-TX), US Senator John McCain (R-AZ), and former Massachusetts Governor Mitt Romney take part in the CNN/Los Angeles Times Republican presidential debate at Ronald Reagan Presidential Library in Simi Valley, California January 30, 2008. Air Force One used by Reagan is in background. REUTERS/Robert Galbraith (UNITED STATES) US PRESIDENTIAL ELECTION 2008 (USA)