On Sunday, ProPublica's Kim Barker was on CBS Face the Nation to discuss her new investigation on 501(c)(4)s and the tactics they use to underreport their political activities to the IRS. Already these nonprofit groups have spent more than $71 million on TV advertisements under the guise of "education" or "issue advocacy," trumping all super PACs combined.

"Nobody's actually talking about it," Barker said on the program. "It's just sort of accepted that this is the way it is. You have all of this anonymous money coming in and there's nothing we can do about it...We've seen it since 2010, we're going to see it to a much greater extent in 2012."

Barker was also on Democracy Now! and WNYC's The Brian Lehrer Show this morning to talk about dark money groups and how they exploit their tax-exempt status to keep the identity of their donors hidden. You can read her article, How Nonprofits Spend Millions on Elections and Call it Public Welfare, and all of ProPublica's reporting on Campaign 2012 on our series page.