Sen. John McCain won Saturday's South Carolina Republican presidential primary, AP projects. Fox News and NBC News exit polls ranked the economy as the top concern among South Carolina primary voters, followed by illegal immigration, the war in Iraq, and terrorism. Columnist and Weekly Standard Editor William Kristol commenting on Saturday's results on the Fox News Channel said that the Republican field is now winnowing down to just three viable candidates: McCain, Mitt Romney, and Rudy Giuliani.
