Obama: Under-Achiever?

Nate Silver's take:

If Obama is underperforming a Generic Democrat, that is presumed to reflect some or another weakness of Obama's. But it could just as easily reflect some or another strength of John McCain's -- such as his perceived moderation. Since Obama was polling ahead of non-McCain Republicans by blowout margins, I would argue that the latter is more likely.

McCain was the smartest credible pick for the GOP, and his residual reputation for moderation and independence is still working in his favor. McCain's real danger is looking more like an establishment Bush/Rove Republican. Which is why picking Romney for veep would probably sink him.