From Paul Krugman in the New York Times:

"In Florida, in particular, the rolling estimate produced by the professionals at Pollster.com shows Mr. McCain running substantially ahead of Mr. Obama, even as he runs significantly behind Mrs. Clinton. Ohio also looks problematic, and Pennsylvania looks closer than it should. It’s true that head-to-head polls five months before the general election have a poor track record. But they certainly give reason to worry.

The point is that Mr. Obama may need those disgruntled Clinton supporters, lest he manage to lose in what ought to be a banner Democratic year. So what should Mr. Obama and his supporters do?

Most immediately, they should realize that the continuing demonization of Mrs. Clinton serves nobody except Mr. McCain. One more trumped-up scandal won’t persuade the millions of voters who stuck with Mrs. Clinton despite incessant attacks on her character that she really was evil all along. But it might incline a few more of them to stay home in November."