of cases pressed by obscure 1982 ruling by the agency. they may legally make up to 49% of their expenditures political in nature and accordingly come to play a large role in modern campaigns. one of them, american crossroads founded by fox news contributor karl rove raised $70 million in the 2010 cycle. >> i am unaware of any donors to american crossroads with a letter. there are 137,000 such organizations across the political spectrum. a lot outside of politics. i'm highly skeptical that the i.r.s. after decades treating contribution to 501c4s would suddenly change. >> i.r.s. says the examination are not part of broader effort to look at donation to 501c4 and denied political motive. fox news confirm from two sources two of the five doe no, sir under investigation contributed to freedoms watch, a conservative 501c4 founded prior to the '08 cycle now in inactive. billionaires like george soros on the left and the koch