I do not believe that there is a single group that rules over both [or all] parties, but seperate groups at the top of each political party that, regardless of who is nominated, will rule over that politician and all of his associates. However, I do believe that both democrats and republicans are predisposed to money and power, thus sharing into the same agenda. The day someone "sneaks" into office and steps outside of this realm is the day you will see the next assassination.
As for the various elitist groups mentioned in this forum, take it all with a grain of salt, but by no means should you rule it out.