Jon Chait thinks J Street has a big problem, too:
My main thought coming out of the J Street conference is that J Street has a huge problem on its hands. It's trying to win political influence and compete with AIPAC to speak for the center of American Jewry on the Middle East. Meanwhile, its most enthusiastic supporters have beliefs that are totally incompatible with this goal. J Street has played a delicate political game, sending different messages to different constituencies, but something is going to have to give.