What is the gravest threat to our democracy? Some say Iran or al-Qaida. The answer is the grotesque Citizens United decision of the Supreme Court. The court asked, "Do we need to give corporations even more influence over our political system?" The majority decided that, in the guise of free speech, corporations and the wealthy needed to be able to spend unlimited amounts to affect elections.
The real justification is the huge cash advantage to the right wing. It is now possible for a single billionaire or corporation to overwhelm the contributions of millions of citizens.
The solution to corruption is to remove the money. We need to overturn Citizens United and have publicly financed elections with reasonably short campaigns (months not years), so politicians can focus on solutions and not on raising cash for the next election and advocating corporate interests over the well-being of citizens.
Ask every candidate their view on this issue and vote accordingly to save democracy. Think, then vote.