No, we don't need another Israel lobby.
If the Israeli-Palestinian conflict is ever to be "solved" in a judicious manner, it's going to come about from the effort of forces who are not aligned with Israel out of the gate. Because when it gets down to it, Israeli doves and hawks have long been in agreement about the prudence of grafting a "secure Israel" over the lives and livelihood of Palestinians. Their disputes are mostly tactical, and tangential.
I fear that all J Street is going to give us is more clucking from Dennis Ross, et al. and hand-wringing over why Palestinians don't jump at whatever "generous offer" of a ghettoized, cantonized state is in vogue this time around. Surely, that's not going to help the situation.