Tea party affiliates were taking up too much of their time.
Check it out:

In 2011, while the Internal Revenue Service (IRS) was busy scrutinizing the tax-exempt status of 100 percent of Tea Party groups and other conservative non-profits, the tax agency did not audit a single high-value electing large partnership (ELP) with more than $100 million in assets.

That’s according to a preliminary report released to Congress by the Government Accountability Office (GAO) April 17th. (See GAO.pdf)

An ELP is a business entity with more than 100 partners and more than $100 million in assets that is required to file a 1065-B tax return every year. They include large private equity firms, hedge funds and oil and gas partnerships.