A composite image shows part of the NPR/Center for Responsive Politics reporting team's whiteboard at NPR headquarters that was used to map out how Wellspring connects to other social welfare groups. (Click the enlarge button to see a full-size image.)
John W. Poole/NPR
The Au Sable River in Michigan is a popular place for fly fishermen and the heart of a debate unexpectedly influenced by largely invisible social welfare organizations.
Tea Party activists gather on Capitol Hill in 2011. A surge in applications for 501(c)(4) status in recent years has revealed sometimes murky and contradictory rules governing the political activities of tax-exempt groups.
Brendan Smialowski/AFP/Getty Images
Republican U.S. Senate candidate Dan Winslow of Massachusetts wants same-sex married couples to have the same right to pool their money for political donations as other married couples. But the Federal Election Commission says the Defense of Marriage Act won't allow it. The constitutionality of DOMA is now before the Supreme Court.
Senators Lisa Murkowski, an Alaska Republican, and Ron Wyden, an Oregon Democrat, discussing their new campaign finance legislation at an April 23, 2013 Capitol Hill news conference.
Chip Somodevilla/Getty Images
A woman views a Mitt Romney campaign ad in September, a month after the launch of an online government database that is supposed to make it easier for the public to see what political ads air in big markets, and how much is spent on them.
Karen Bleier /AFP/Getty Images