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If you feel that a candidate isn't like you and doesn't see the world as you do, then you doubt that once in office, he will work to perpetuate (if you are conservative) or transform (if you are liberal). And you fear he will do the opposite.
From experience, voters are cynical about government's ability to alter the economy and create good jobs. So promising those things doesn't profit a candidate. But voters know first-hand government's ability to reach into their lives and change the social fabric: Bus your kid miles to integrate a school. Let women kill babies (yeah, I know). Allow that weird gay couple up the road to adopt a little boy, and now we've got GLBT sensitivity training in the 4th grade, forchristsake! Ban guns.
So don't expect Obama to make gains in rural America. Those folks correctly see Obama as being different from them. But the difference has little to do with his race and Harvard education.