Then there were the attacks on Clinton that bordered on the personal. For example, the statement, "I don't want to spend the next year or the next four years re-fighting the same fights that we had in the 1990s." Or the line, "I am not in this race to fulfill some long-held ambitions or because I believe it's somehow owed to me." (Full text here.)

But you'll notice one thing: Hillary Clinton is never mentioned by name. Obama continues to observe the piece of campaign trail etiquette that keeps candidates from naming the subjects of their critiques. John Edwards has chosen to ignore that little brocard, and incidentally, is seen by many as the underdog currently drawing the sharpest contrasts between himself and Clinton.

Perhaps Obama needs to do the same if he hopes to be effective. After the speech, I asked an undecided voter who was leaning towards Obama what she thought of his attacks on Clinton. After a pause, she said, "I didn't notice that at all. And I'm usually pretty sensitive to that sort of thing." And when I asked the same question to a Clinton supporter standing nearby, she just stared at me blankly.

Later, I caught an Obama supporter outside an afterparty. "I don't know if I would call them attacks," he said of the lines above. "I think at this point in the game all three frontrunners are just trying to separate themselves." I'm saying here that Obama will have to "turn up the heat" if he's going to do that with any real results.