Obama really hasn't really explained his "bitter" comment - - can't, because what he meant was people turn to hot-button religious issues and gun rights and immigration bashing when they feel that government won't help solve their real problems. He didn't mean that 'religion' is a crutch, but that voting on the basis of abortion and gay marriage (and gun rights and keeping illegal immigrants out) is. And that is genuinely insulting to people who base their votes primarily on those issues.
Tonight, at the 'Compassion Forum' (read: test of religion) at Messiah College in PA, he said in effect that he didn't mean 'cling' in a bad way (it's good to 'cling' to religion and tradition in times of stress), and that's ridiculous. That's not what he meant.
I do think he can wriggle out of the 'elitist' frame by stressing that he spent years working intimately and not from on high with poor people. Everyone from his past whom reporters have dug up says that he listens to people, works with them rather than trying to dictate solutions, engages as a human being. Maybe it's more important to say "I'm not an elitist" than to try to explain what he said.
It should also be remembered that no one can go through two years of campaigning without making gaffes, and I can't think of any prior ones that Obama has made. Because he's the front-runner Hillary's in overdrive to blow this sky-high, but her oft-repeated Bosnia fantasies were far worse, and McCain's errors, reversals and mask slips are breathtaking - a complete 180 on helping distressed homeowners after giving a ridiculous speech telling them to eat cake; repeatedly mixing up Sunni and Shia; breaking into 'bomb bomb Iran' song. If Obama can't survive a gaffe, the country doesn't want to vote for him.