The Atlantic's Marc Ambinder has some bad news for Democrats, based on early exit poll results from Indiana and North Carolina. On his blog, Ambinder writes:

Forget the horse race numbers for a moment: if the surveys are accurate, the polarization within the Democratic Party has reached critical levels. Nearly six in ten Obama supporters in Indiana say they would be dissatisfied if Clinton were the nominee -- that's (I believe) the high percentage of Obama supporters who have ever said that.

In both IN and NC, two thirds of Clinton supporters say they'd be dissatisfied if Obama were the nominee -- I believe that's the highest number recorded for that question, too.

The percentage of Clinton voters who say they'd choose McCain over Obama in a general election is approaching 40% in Indiana. Put it another way: in North Carolina, less than HALF of folks who voted today for Hillary Clinton are ready to say today that they'd definitely vote for Obama in a general election.

For the moment, you should take this with a potentially heart attack inducing amount of salt. As noted, these are early results from the exits, and they're subject to change as the night goes on. Also, while a bitter primary will lead voters to say these sorts of things, in the past they've typically come back to their party's candidate. Remember the bitterness that marked the Republican primary this year? (I know it seems like it's been a decade, but seriously, it was only a couple months ago when it seemed like Mitt Romney's voters would never come around and support John McCain.)