Political Dichotomy

Why is it that when a black man gains power here in the States America's Republicans, "moderate" conservatives and far right conservatives suddenly shift further right and tie up they belts? Obama pledged for bi-partisanship and instead provoked an America that has become a nation of political dichotomy. You are either far right or far left. There is no gray area or no middle field. If you by any chance appear to be playing both fields your party suddenly turns their back against you. Look at former Republican Spector or former Democrat Lieberman.  Instead of coming together our nation has broken down into two strong opponents trying to strengthen and restore their own power while America has fallen into one huge hole. Was this a black man's election to the highest seat available in our government or is it America's stubbornness to work and build a nation together as a whole?