For the moment, former New York Mayor Rudy Giuliani sits on double-digit leads over the rest of the Republican presidential-hopeful pack in several national polls. Why? "It appears to me that Rudy is going aggressively after the conservative vote," says Pennsylvania Republican and former U.S. Sen. Rick Santorum. "He has not ceded that ground to anybody." Santorum, known nationally for his social conservatism, says Giuliani does a good job of reminding people how he governed as a conservative on crime, welfare and taxes in New York City. Santorum also believes Giuliani has scored points on social issues with his comments...