Both the Repubs and the Dem. parties are going through major transitions at the moment.
The Dems have been co-opted by Communists or "Progressives", as they like to be called now.
The Repubs are currently shedding the religious right in favor of a more Libertarian stance. Freedom for all on social issues ie, "Who gives a shit if gays want to marry?.." and emphasis on the free market.