I've been meaning to write for months that Citizens United will primarily harm democracy below the radar, but Ezra Klein's gone and done it for me:
....even at the end of the [congressional election] campaign, many potential voters will know very little about their congressional candidates. They will be susceptible to ads telling them terrible things. Some of those candidates won’t have the resources to fight back.
No one knows that better than the candidates themselves. Both incumbents and potential challengers realize that a deep-pocketed PAC could decide their race. So when they get a call from that PAC’s director urging them to support this or that, they’re that much likelier to listen. The result, then, isn’t just that moneyed interests can throw congressional elections. It’s that they wield more influence after the election — and they can exercise that power without spending a dollar.
Read the whole thing as they say. I think state level elections are even more subject to this - don't expect the US Chamber of Commerce to have overlooked that.
Unlimited money from the people who have unlimited money, to make sure the system's rigged to allow them still more unlimited money. Thanks, US Supreme Court.
UPDATE: best we can do now is disclosure, although that might also be under threat. For my fellow Californians, there's the California Disclose Act that would help a great deal if it passes. Best of luck if you live in a Red state, you'll need it.