Voters are too wimpified to step out of their comfort zones. They'll vote for the BAD politician time after time after time because of their fear of the terrifying "unknown." One would think that pot has been legalized nationwide by watching the voting trends. It's disgusting.
It goes way beyond that.
In NC massive voter fraud was uncovered. People were found with the same names and social security number voting multiple times and in multiple states.
Then you have the IRS scandal. Obama was targeting conservative groups come election time, denying them of funds and auditing and harassing them so as to help them win elections.
Gerrymandering still goes on.
Simply put, to get elected you must sell your soul to the powers that be. Once they have their puppet in there, they will see to it that they stay. I'm sure that there are many other tricks to rigging elections. In fact, I remember back when democrats were accusing Obama of trying to buy them off so that weak incumbents could still win. This happened in both PA an Colorado.