The reasons Obama’s "bitter" gaffe could hurt him have been widely enumerated . In a nutshell: It creates the centerpiece of the Republicans’ general election case against him. Coupled with Rev. Wright, the lapel pin, the pledge of allegiance, the persistent Muslim rumors, and his race/name, the charge of elitism is a Swift Boat campaign waiting to happen.
But there’s another vulnerability in his remarks, and that’s the optimist/pessimist factor. In any election, pretty much no matter what the circumstances, voters are going to favor the optimist. Jimmy Carter’s "malaise" speech may have nailed a core truth about the state of the union, but come on, what a downer. As Joe Klein pointed out , "When Ronald Reagan touted 'Morning in America’ in the 1980s, Dick Gephardt famously countered that it was near midnight 'and getting darker all the time.’ " Who wants to hear that? If Americans wanted to be depressed, they’d elect Eeyore.
That’s one reason Obama’s campaign has succeeded so far—"hope and change" is more compelling than "judgment and experience." But "bitterness" could easily become the new byword of critics looking to undercut his message of (some would say misguided) optimism. Clinton says the Pennsylvanians she has met aren't bitter—they're hopeful. John McCain is already intimating that bitterness is somehow the opposite of patriotism. Of course, Obama would argue that bitterness and optimism—not to mention patriotism—aren’t mutually exclusive but that together they make change possible. It's been part of his message all along. Which is why the "bitterness" aspect isn’t likely to do much lasting damage to Obama—among a certain population slice, the man is synonymous with optimism.
If this episode manages to tar Obama, it won’t be for the "bitter" part. It will be for pairing "guns" and "religion" with xenophobia and racism. That’s where Clinton is hitting him now and where McCain will hit him in the fall.