Yes, it's only one poll (and a Rasmussen poll at that), but Democrats cannot be happy to learn that McCain now leads Obama by seven and Clinton by ten in hypothetical match-ups.
The Clinton campaign is probably right in assuming that the only way they can win the nomination is to destroy Obama's electability argument with superdelegates. The obvious problem is that intense campaigning and attacks may hurt her popularity, too. But the Clintonites should be wary of Drudge headlines like "McCain now leads by double-digits" for another reason. If superdelegates begin to think that the party is blowing it's chance at the presidency, it's all the more likely that they will want to end this tiresome primary sooner rather than later.