i'm wolf blitzer, you're in "the situation room." we're live here at constitution hall, here in the nation's capitol, where in just a little bit more than 24 hours, the republican presidential hopeful will face off for the first time in a major debate on national security, foreign affairs and the economy. he will be mod rating the event co-sponsored by the her kaj foundation and american enterprise institute. on the eve of this critical contest an eye-popping shift? the republican con taft. a new cnn poll just released minutes ago, shows newt gingrich on top of the republican pack fo...