jeddy - The American political structure seems to have evolved so that only two major parties can share the stage at any one time. Originally we had the Federalists and the Democratic-Republicans, then Jackson took the Democratic-Republicans into left field, they became the Democrats and the Whigs popped up. The struggle between the Whigs and the Democrats ended with the election of Lincoln, the first Republican, and the Democrats and the Republicans have been the only major parties since that time. No other party can get a foot-hold, because the Dems. and the Reps. aren't much different. If an outside party starts to gain momentum, they band together to drive the new guys out.
               To many of us, it seems like we simply have a one party system.