I'm surprised how often I hear this complaint from disappointed Democrats. But what kind of president did he promise to become? During the 2008 campaign, when you compared his concrete policy proposals with Clinton's and Edwards's, two points emerged quickly and clearly: First, there wasn't that much difference between the three of them. Second, to the extent that there were differences, Obama's proposed policies were consistently the mellowest, most compromising of the three. Why did you believe that "change you can believe in" wasn't a bumper-sticker slogan, but a credible prediction?
It's true that Obama's positions weren't very different from those of his competitors, but then just because Obama's promises were a lot like theirs doesn't mean that he didn't make promises.
In any event, we all know about Obama's promises
-- the ones he has kept as well as the ones he has broken. But we can't ignore that much of his campaign was about the implicit message of his candidacy. For instance, when he promised to close Guantanamo, it wasn't just a campaign promise. Implicit in that promise was the message that "I'm not the same kind of guy as George W. Bush: my administration won't lock up people without due process, won't torture prisoners, won't launch unprovoked attacks against Mideast countries." I think people were entitled not only to rely on the explicit promise (which Obama broke), but also on the implicit message about the kind of president he'd become (which Obama betrayed).
It's also true that Obama said that he'd be a conciliator, that he'd end the partisan divide in Washington. I'm not sure if anyone fully realized how incompatible that was to the specific policy statements he made on the campaign trail. There was always this divide between policy and process, and maybe Obama was deluded into thinking that he could bridge that divide -- and maybe, in the end, he managed to delude his supporters as well. But it was only after he took office that it became clear that, for Obama, process was
policy, and that, faced with the choice, he'd sacrifice policy for process every time.