I am totally against the Supreme Court's Citizens United ruling, because to me "free speech" has turned into a bought-and-paid-for commodity, but there are arguments from the left on both sides of the issue.
I've had some experience with trying to buy ad space during elections, and as the days creep closer to one, the ad space becomes more expensive, for the most part. At least in my experience.
My question is what happens when Big Corp decides to buy up the last month, or two or three, of available ad space on all major media outlets for a particular election? That would have an incredible impact on either an election or like we have in California, a proposition. We saw what happened when the Mormons bought up a ton of air time in California to oppose Prop. 8
We need regulations in politics, just like we need them for Wall Street and just like we need them when you buy a car. Hopefully, Congress will act and pass much needed legislation to help preserve our Democratic process. It already is deeply flawed, but this ruling only makes it worse.