From James Fallows, writing in The Atlantic…

The Clinton team doesn’t worry about hurting Obama’s prospects of winning in the fall, because they assess those prospects at zero. Always have. Obama might not win if he leads a bitterly divided party, but (in this view) he was never going to win. Not a chance. He would be smashed like an armadillo in the road by the Republican campaign machine, and he would be just about as ready as the armadillo for what was coming.

When Clinton still had a plausible shot at the nomination, this assumption removed all guilt from beating up on Obama. As in: “I have a lifetime of experience that I will bring to the White House. I know Senator McCain has a lifetime of experience to bring to the White House. And Senator Obama has a speech he gave in 2002.” By whittling Obama down, the Clintons were saving the party from a suicidal mistake.

And now that Hillary Clinton no longer has a plausible chance, she (and Harold Ickes etc) don’t need to wake up in the middle of the night and worry: Oh no! Maybe we’re paving the way for George Bush’s third term! They are sure that Obama’s nomination means exactly that, no matter what they do. So by definition they can’t be making things worse. It is like sticking pins into a corpse — you’re not really hurting it any more. And if these efforts in fact make Obama’s victory less likely — well, then, reality will conform to their preexisting view…

As it happens (and as Fallows belatedly acknowledges) others got here before him.