IRS acting commissioner Steven T. Miller has an op-ed in USA Today today reiterating the IRS’s position that “mistakes were made” in its targeting of tea-party and conservative groups. He acknowledges that the IRS “should have done a better job” in its handling of the issue, and attributes the mistakes that were made to “the absence of a sufficient process” and “a lack of sensitivity to the implications of some of the decisions that were made”:

Mistakes were made, but they were in no way due to any political or partisan motivation. We are — and will continue to be — dedicated to reviewing all applications for tax-exempt status in an impartial manner.
We sought to centralize work in this area in 2010 because our office of Exempt Organizations observed a sharp increase in the number of section 501(c)(3) and 501(c)(4) applications coming from groups potentially engaged in political campaign intervention. Between 2010 and 2012, the number of applications for 501(c)(4) status more than doubled, from 1,591 to 3,398.
Because the law limits and in some cases prohibits political intervention by exempt organizations, the IRS must carefully review applications based on the facts of each case. While centralizing cases for consistency made sense, the way we initially centralized them did not.
There was a shortcut taken in our processes to determine which groups needed additional review. The mistakes we made were due to the absence of a sufficient process for working the increase in cases and a lack of sensitivity to the implications of some of the decisions that were made.