The holiday spirit hasn't spread to the presidential campaigns. In fact, several top-tier candidates are duking it out as the race tightens in key states. Just about every day, Democrats Hillary Clinton and Barack Obama find something new to argue about. And Republicans Rudy Giuliani and Mitt Romney are conducting their own sniping sessions at the same rate. This discord could give an edge to candidates who stay above the fray, especially in Iowa, where voters dislike negativity. So watch for Democrat John Edwards, Republican Mike Huckabee, and others to tone down their intramural rhetoric and play the positive card as much as possible between now and the Iowa caucuses January 3. They hope that nice guys can finish first.