The recent WaPo (no, I won't give the attention whores a link to their revolting article) article breathlessly repeating "rumors" (lies) about Barry Obama's "ties" (no connection) to Islam is a classic case of Southern Strategy misdirection.
The reason why this meme is being pushed so hard by the Right is because it allows voters to substitute a more acceptable form of bigotry for a less palatable one. It is not acceptable in the US to say you won't vote for a black candidate. Dyed in the wool racists don't care, of course, but many "respectable" voters can't voice this prejudice, not even to themselves. Those who have some modicum of a conscience left will feel inhibited against indulging in that prejudice.
While the surface message about Barry being a Muslim is exactly that - He's one of them islamofascist guys! Just without a turban - and will appeal on a direct level to that very strong prejudice, the real connection is Muslim = black Muslim = black. It is a way of providing a substitute excuse that brings some sympathy if expressed in a way that flat out racism would not. "Oh, I know he *says* he Christian, but what about all those influences on him..." As if Barry Obama is anything other than a corn-fed, Midwest, WASP type (I mean, c'mon, he's a cousin of Dick Cheney for Christ's sake!) who just happens to have a very deep permanent tan.
Anyway, the Muslim meme is cover for the true prejudice (one that is alive and well, as Harold Ford can attest), the original sin of American identity, treating African-Americans as sub-human. Those who want to say "I won't vote for the n*****" can now say "I won't vote for the towel-head," and they will get a pass, most importantly from their own conscience.
And, no, this doesn't mean I have any sympathy for Barry on these attacks. He's been trashing Clinton on with right-wing talking points for the last month. To use the argument that is turned against HRC all the time, if he's not tough enough to take this beating and stay ahead in the polls, he's not tough enough for the general where it will be worse.