Seems to me that both parties have riled up their supporters against each other so much that the best way to remain in the status quo is to make it such that the voters believe that voting for anything other than the two main parties is too dangerous, because every vote counts, or the opposition wins.
It seems to me pretty sad. They both play golf together and party in the weekends and yell at each other in front of the cameras, while they laugh all the way to the bank. Both parties are bad. Seems to me like controlled opposition to remain in power and to not rock the boat, made possible through the American news media. It works like hell, too!