. >> ari, just quickly, michael hersch wrote today that joe biden ranks as one of the most powerful and influential vice presidents in american history. i'm just curious your perspective. you served alongside a very powerful vice president, cheney. whatever you think of the administration's policy, is biden as powerful as cheney was, more powerful, in that category? >> it's hard to know because the vice president's true strength, any vice president's strength is what they whisper privately when they're with the president. i think president obama gives vice president biden a lot of time to be alone to talk to him, at least that's what i hear. it's is he able to influence the president? that's how vice presidents are powerful. you don't know. i don't think this administration talks about it. he's not as visible in that sense so it's hard to know what his real role is behind the scenes. >> appreciate it. thank you very much. day four of john edwards trial. it's fascinating. as the defense tries to hammer away the prosecution's key wins against edwards, a trove of documents is released. det