In fact, the best approach Obama could take now is to hammer away at the idea that with Hillary in the White House, the US will be for sale to the highest bidder--with the #1 lobbyist in the world in the catbird seat. There is no way that Bill will not have influence on a President Hillary Clinton.

And if this is perceived as negative campaigning against a fellow Democrat, he can give the same answer her side gives to that criticism--he is only bringing up the same issues she would have to face in the fall if she were--by some ghastly mistake--the Democratic nominee.