ctdonath has it right. Because of a flaw in our system there can be only two viable political parties. Congress must agree to fix the flaw to get it done within

ctdonath has it right. Because of a flaw in our system there can be only two viable political parties. Congress must agree to fix the flaw to get it done within our system, and Congress has the incentive to never fix. The fix is instant run-off voting, like Australia has.