I'm surprised he's pulling out quite so early - he could still have had a major impact by pulling support from Clinton and acting as king maker at the convention.  However his numbers were going to go south anyway as he had lost all serious hope of winning and most voters won't vote for a loser or spoiler candidate.  From his own point of view this is probably his best move, but will he endorse Obama?  He's hardly likely to want thew VP nomination again, and he is no longer a Senator.  Is this the end of he road for him?

"It's a mystery to me - the game commences, For the usual fee - plus expenses, Confidential information - it's in my diary..."