Senators Barack Obama and Hillary Clinton debate tonight live on CNN and CNN.com at 8 Eastern. For the first nine months of this race we watched Hillary debte as the presumed heir apparent to the Democratic nomination, and she carried herself as such. For a few months now we've watched her debate fully realizing that it has become a legitimate competition. Tonight, really for the first time, we're going to see how Obama debates as the frontrunner for the nomination. It'll be interesting to see how both he and Senator Clinton handle themselves in their new roles.