If you think Muslim=Black I doubt you've met many American Muslims. There are far more Christian blacks in america than Muslim blacks, and most of the "Christian" blacks are totally supportive of Obama.
Countries like Tonga, Samoa and even Chile have a significantly higher concentration of Mormons than the 2% or so in the United States. So I don't think it is entirely or even largely a race thing.
If the real Amish voted in large numbers, I suspect their approval rating of Obama would be as low as the Mormons, judging by the Amish I know here in Pennsylvania. People who stress self-reliance generally have little use for Marxist redistributionists.