The obvious fact is that the GOP is totally terrified of being accused of being racist. McCain categorically denounced the mention of Rev. Wright in GOP ads back in April. Wright’s name wasn’t mentioned at the GOP convention or in any of the debates. That’s why he’s ranting on about William Ayers, whose connections to Obama are much more tangential than Obama’s connections to Wright. (Indeed, Sen. Obama gave over $53,000 to Wright’s church in 2005-2007 according to Obama’s tax returns.) But, Ayers is white, so he’s okay to attack, but Wright is black, so he’s off-limits.
In fact, this anti-anti-black mindset even extends into the emails from the fever swamps. Consider the popular one that claims that Obama isn't black, that he's 8/16th white, 7/16th Arab, and only 1/16th African. Obviously, if you take one look at a picture of his father, you can see that's not true. (He might have a tiny bit of ancestry from an Arab slave trader that his African ancestors sold black slaves to, but it sure isn't 7/16th.) Obama calls his father "black as pitch" and refers to his father's tribe as "as ink-black Luo."
Or consider all the emails about Obama being a Muslim.
Now, the truth is that Obama has had far more sympathetic contacts with Muslims than most Americans. But his sympathy for Muslims has had zero to do with their religion and everything to do with their being, in his mind, anti-European white. As he admits in Dreams from My Father, he tended to get Muslim and Black Muslim (whom he liked a lot) mixed up in his mind.
For example, here's what Obama wrote at age 33 about his visit around his 28th birthday to Kenya, where he learns from his step-grandmother, to his horror, that his Muslim grandfather Onyango Obama had worked as a servant for British colonists:
I knew that, as I had been listening to the story of our grandfather’s youth, I, too, had felt betrayed. My image of Onyango, faint as it was, had always been of an autocratic man-a cruel man, perhaps. But I had also imagined him an independent man, a man of his people, opposed to white rule. There was no real basis for this image, I now realized -- only the letter he had written to Gramps saying that he didn’t want his son marrying white. That, and his Muslim faith, which in my mind had become linked with the Nation of Islam back in the States. What Granny had told us scrambled that image completely, causing ugly words to flash across my mind. Uncle Tom. Collaborator. House n*****.