>
>There is no Constitutional rule that requires any party at all. We seemed to have settled on 2 major parties, although throughout our history we've had more. And even today, there's the Democrats, the Republicans, the Libertarians, the Green Party....and proabably several more that I'm forgetting right at the moment.

Here is a list of our politicial parties.

http://en.wikipedia.org/wiki/List_of_political_parties_in_the_United_States