A friend of mine recently commented on the need for a third political party. There are a few problems with this.
First, the US generally has a "winner take all" (non-proportional) vote system that naturally leads to two parties.
Second, by poll numbers, the Libertarian Party shows the most viability, but many true libertarians (small 'L') don't believe in voting and have no interest in politics. Good luck trying to get that crew to go toe-to-toe with the Democratic and Republican machines.