A couple of observations about the sexual harassment allegations against Cain.
1. If this is the result of a leak by one of Cain's rivals the most likely candidate is another GOP'er. Getting it out now is of zero use to Obama, who can't even be sure that Cain will be his opponent in the general election.
2. The hope of Cain's enemies has to have been that his notoriously disorganized campaign would spin apart when the first scandal hit but
3. If Cain can emerge from this still standing he'll have gained tremendously. In a perverse way these allegations could end up helping Cain at the national level because they keep him in the spotlight. If he survives it will be by strength of character rather than political spin simply because his organization is so rudimentary and unpolished that spin is beyond them.
4. Don't forget that far worse allegations came out about Clinton in 1992 and he still survived to take the Democratic nomination.
Finally, check out the video of Cain singing at the National Press Club. In a lifetime of watching politics this has got to be one of the most unusual things I've ever seen. But what really struck me was two things: First, the CSPAN cameraman doing a perfect slow zoom out while Cain sings. And the second being the fact that when he was done the audience (largely journalists) stoop up and cheered.