Matt Cooper argues that Obama risks losing the hope and change mantle if he keeps talking about math:
If I were Obama, I'd stop arguing it's over and say, "Okay, let's keep this discussion going." (It's gonna keep going anyway.) You're still the candidate of the past. You still supported NAFTA and voted for the war. He should show he's tough enough on national security by finding some issue where he can get to the right of her. (Putin? Kosovo?) The more people see Obama the more they'll probably like him. So roll with it.
Couldn't agree more. Obama must not let the Clintons into his head. He has to make this campaign about his positive ideas again. Their goal is to destroy his inspiration, to make this election about who you're most familiar with in a world of nasty Republicans and nasty Islamists. His goal must be to swamp them, as he has already, with his talent, his reason, and his optimism.