First off, don't believe them. That said, the results seem to indicate that racial polarization has reached an unprecedented level. Ambinder:
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. The basic demographic breakdowns suggest that the black/white split has widened as well (although I can't say too much about that now), which might mean that racial polarization (along with SES polarization) is driving the Democratic race to an unprecedented degree.
Sounds to me like a best case scenario for McCain. Hillary probably isn't going to win this thing, and if she were to pull it off there's not much evidence that McCain could beat her in the fall. Right now she outpolls Obama across the board. So the hope is that the Democratic party becomes so divided that even in an atrocious year, a moderate and likable John McCain can steal the election. A split tonight pours $4.00 a gallon gasoline on that fire. One thing that jumps out at me: Indiana seniors favor Clinton by 78-21. McCain's age is going to be an issue, but the Dems may overplay their hand and spark a backlash among a group that is already disinclined to Obama. McFogey Democrats!