I don't think that it's fair or reasonable for the Obama campaign to be held responsible for this. I've not detected sexism coming from them toward Senator Clinton, certainly in any systematic way. I suspect they have been quite conscious of not going there, which is to their credit. Many Clinton supporters feel that Obama has benefited from the sexism in the media and should have stood up to it, but I just reject that. Both he and Clinton are fighting hard campaigns for the most important job in the world and they are not obligated to defend their rivals while the battle rages. (It might have behooved the progressive movement to have done so, however.)
Unfortunately, at this point I think the media is actually hurting the Obama campaign with their continued sexist coverage. He is trying to reach out to her supporters and the press is making it much harder for him by keeping this hostile, demeaning discussion --- particularly this endless call for her to drop out --- roiling in the ether. The party will work this out, but the media, as usual, is making things worse.
The discussion on blogs has too often degenerated in to "Your candidate sucks!", "No, your candidate sucks!" flame wars. They often reach in to the grab-bag of right-wing talking points to elaborate on why the other person's candidate sucks - she's a "rhymes-with-witch", he's "bigger" (snicker, snicker) - and we end up perpetuating this crap. While I support Obama, I have not and will not write a word against Sen. Clinton for the simple reason that I have known since last summer the level of invective that would we tossed her way, and I in no way wanted to contribute to that. Besides that, I do not support Sen. Obama to be "against" anyone, but for Obama. I do not do any favors to anyone by running down Sen. Clinton. What's the point of that?
To the media types who are all upset because the Clinton campaign is pointing out what is quite clear to so many people, all I can say is I don't have a hanky to spare for you because they are being so unfair to you. When a political operative can sit on a cable news show and say that some women deserve to be called "bitches", and not have his mic cut and the "journalist" doing the interview apologize to viewers, I think that says all that needs to be said. I will only stop criticizing the media when someone else gets on CNN or MSNBC, says that some nationally broadcast journalists are assholes, and isn't poo-pooed.