ACLJ, in an August 2012 article “U.S. Senators Demand the IRS leave the Tea Party alone“points at Democracy 21 and the Campaign Legal Center as pressuring the IRS to do the wrong thing. 

Fast forward to July 17, 2012 when the IRS responded to an inquiry from
liberal groups Democracy 21 and Campaign Legal Center by saying that it
would consider changes to the tax treatment of social welfare groups. 
This reply was sent despite the fact that the IRS has given no public
indication of considering such a change, has not requested public
comment, and has not communicated that this is among their current list
of priorities.