John Mearsheimer, a professor of political science at the University of Chicago, co-authored The Israel Lobby with Stephen Walt. The book was a breakthrough if only because it brought out in the open what Washington DC insiders have known for decades.
He is always worth a listen because he speaks clearly and concisely and, I believe, makes a good case. In this short (13 minutes) interview, Mearsheimer sums up very well the ongoing power of AIPAC as illustrated by the current humiliation of President Obama. He also explains his view that Israel will become an apartheid state.
Should you want to hear more from Mearsheimer, I recommend a full hour video presentation of his, The Future of Palestine: Righteous Jews vs. the New Afrikaners