What if you disagree with Obama's ideas? Are you suddenly against hope? Given recent events, it seems that if you're not with the Obama program, you're fair game for tarring as a crypto-racist. And that's what Obama supporters are willing to say about the Clintons! (Of course, I can barely scrape together two molecules of sympathy for the Clintons. They've been playing games with race for years, using the same tactics against their enemies that the Obamans are now using on them.) If Obama becomes the Democratic nominee, imagine what hairballs will be coughed up at the Republicans.
Unity around an issue - war, health care, education - is a legitimate appeal. But you can't defend America with hope; you can't heal people with unity. Further, it is morally antithetical to democratic values to demand unity for unity's sake. And it is quite literally impossible to govern that way.
(The irony here is that liberals have been complaining for years that the GOP too often appeals to voters' patriotism, yet they don't object to Obama's appeal for unity. Idealistic unity for all Americans - isn't that just a no-frills version of patriotism?)
So far, not even all Democrats have embraced Obama's gassy rhetoric of hope and togetherness, so there's no reason to suspect that Republicans and independents will rally around those themes during an Obama presidency, at least not for long.
This is one area where I agree with New York Times columnist Paul Krugman. In his book "The Conscience of a Liberal," he argues that progressives have one distinct set of priorities and conservatives have a very different set, so both have to be partisan if they want to get their way. There's no reason people can't be well-mannered and open-minded in their disagreements, but the more important priority is that both sides should give their view the strongest argument they can and not give a fig about bipartisanship for its own sake. Agreement on that point is all the unity we need.