The right has manipulated and limited the range of political perspectives via simple repetitive message pounding in public media.
What they've done is simple genius. At some point in history, the conservative right (old money, establishment, elite) adopted a strategy to redefine the liberal left. They attacked the moderate middle with relentless finger pointing, name calling, and accusations of being liberal leftists. And they haven't stopped to this day.
What they have achieved is a two party system that views moderates as leftists. Thus even when the right is not in power, the most radical policy changes introduced by the opposition are no more than reasonable compromises. Furthermore the true members of the liberal left are continuously disappointed by their party because their leading officials are actually moderates. By establishing moderates as the left in the public media/mind, the actual liberal left become viewed as crazy extremists.
Im not explaining this very well, but this phenom is why the US population feels so disenfranchised and disillusioned with our government, no matter who is elected.