NPR is doing a series on this election cycle’s spate of anonymous attack-ads. Here’s the jist of the problem:

Two such groups advertising in Pittsburgh are Americans for Job Security and the U.S. Chamber of Commerce. Both are 501(c)s, organized under the tax code as nonprofits. The law says they can’t engage in politics as their primary purpose. It also says they can accept unlimited donations and don’t have to report their donors. Couple that with the U.S. Supreme Court’s Citizens United ruling, and you have a wide-open path for corporate money to flow into partisan politics.

Here’s an interesting tidbit buried at the bottom of the story (emphasis mine):

The ads in Pittsburgh attacked candidates of both parties, but the ones attacking Republicans were all from Democratic candidates or party committees, groups that have to disclose their donors. Not one ad from the supposedly nonpolitical groups attacked a Republican. All of those ads are aimed at Democrats.

NPR: ‘Nonpolitical’ Groups Target Democrats In Ad Blitz

And yes, attack ads do work. Read Everything You Think You Know About Politics and Why You’re Wrong for some insights into political campaigns.