There are of course other factors, but claiming anything in the background decisively pulling the strings is FUCKING RETARDED.
Lobbyist groups broker backroom deals every single day. It's what they're designed to do. Elections in the US are cyclical and have very little (if any) effect on public policy.
50/50 splits are part of the kayfabe to keep the illusion going. The general public is not really part of the process.