Contra Noam and Mike and Isaac, I think the Obama campaign pretty much had to respond to the New Yorker cover. If it hadn't, then when Human Events or Confederate Yankee or some other bad actor started using the New Yorker cover--or came up with a similar image of their own making--they could argue that they were just doing what the New Yorker did, and the Obama campaign didn't object to that. Having made the decision that it's going to be eternally vigilant about this stuff, the Obama campaign has to go after pretty much everything. That said, calling the cover image "tasteless and offensive" might have been over the top. Perhaps they should have just left it "tasteless" or maybe even "not particularly funny."
--Jason Zengerle