Marc Ambinder makes the case:
The superdelegates want a “winner,” a candidate who can beat John McCain winner and not a “who got the most delegates or votes” winner. If HRC wins Pennsylvania by a healthy margin and stays in, by the time June 3 rolls around, she’s likely to have closed the popular vote gap a lot and the delegate gap a little.
But the superdelegates won’t have any additional information about who is best positioned to take on John McCain.
Rationally, why would they decide in June? Wouldn’t it make more sense for them to wait as long as possible to see how each candidate polls against McCain or fares in the press over the summer months?
In other words, if it’s a winner they want, they’ll arguably have MORE information to make that decision the LONGER they wait.
I’d have to disagree with Ambinder here. If Democratic superdelegates are interested in producing an electable candidate, they would be wise to make theire decision in June, because either candidate would be a weaker general election candidate if the nomination battle dragged on until the end of August. That would further divide the party, and give the nominee just over two months to untite the party before Election Day.