Delaware Senator Joe Biden
Had line of the night slamming Giuliani on 9/11 ("There's only three things he mentions in a sentence: a noun and a verb and 9/11. I mean, there's nothing else") and saying the former mayor is unqualified to be president. In that instance, he was at his best: so great and so honorable, in his own wacky way. But lacked his Iraq mojo from past debates — and he seemed to disappear for a very long stretch in the middle of the forum.
—by Mark Halperin