Les Gelb offers the usual valid criticisms of Mearsheimer and Walt, some of the usual invalid criticisms, and then adds on this novel one:
Most unbiased students of the matter would probably agree that the lobby is the single most influential force on American policy toward Israel. But among lobbies in Washington, it is one among many strong players. It is almost certainly less powerful than the pro-Taiwan China lobby, which successfully blocked American contacts with China, or even talk of it, throughout most of the cold war.
A reader remarks that this must explain why the US has so stubbornly refused to let the PRC have its UN seat, even while we almost never cast our veto on Israel's behalf.