 In many ways, the White House has set the president an impossible task, a big boy press conference, in the words of his spokesperson, on which everything now seems to ride. It's his first in eight months, and few would argue that he was a gaffe-free performer, even at the height of his powers. Also, the problem is that so much has already been said, which cannot be unsaid, that it would require a performance of gargantuan proportion...