IRS Targets Donors to Politically Engaged Nonprofits

The Internal Revenue Service is beginning to enforce taxes on gifts to 501(c)(4) organizations, a move that could significantly affect the world of money in politics.

Various 501(c)(4) nonprofit groups such as the the American Action Network and Crossroads Grassroots Policy Strategies have poured millions of dollars into federal election campaigns, even though they are not, by law, supposed to have a primary purpose of engaging in political activity.
http://www.opensecrets.org/news/2011/05/irs-targets-donors-politically-engaged-nonprofits.html

and this democrat org, which may just be exempted under Obama’s plan

Deep-Pocketed Democratic Donors Among First Supporters of New Liberal Super PAC, Nonprofit Operation

The first prong is the nonprofit organization called Priorities USA. Since Priorities USA will be registered with the Internal Revenue Service under section 501(c)(4) of the U.S. tax code, be allowed to keep information about its donors secret. At the same time, it will be allowed to produce electioneering communications and issue ads that mention federal politicians but don’t expressly advocate for their election or defeat. And furthermore, it will be able to fund independent expenditures — advertisements that do overtly advocate for or against federal politicians. Under federal law, the group should not have a primary purpose of engaging in politics, although many 501(c)(4) organizations spent a considerable amount of time and money engaging in political activity anyway.