Money Has Little Influence on U.S. Politics
[C]onventional wisdom, especially among progressives, is that money can buy elections. The Citizens United case was supposed to be the end of democracy since it meant unlimited corporate spending on elections. If money really did buy office, 2012 should have been great evidence for the hypothesis.
Instead 2012 looks like a case study in the powerlessness of money, in the triumph of the autonomous voter. For instance, the Sunlight Foundation reports that 2/3 of outside cash was spent on losers.