Republicans are training their attacks on acting IRS Commissioner Steve Miller amid new revelations that he and the agency’s former top official knew employees were targeting conservative groups but failed to notify Congress despite repeated requests.

Utah Sen. Orrin Hatch, the top Republican on the Finance Committee, and 10 other GOP lawmakers wrote to then-IRS Commissioner Doug Shulman on June 18, 2012 demanding answers about why the agency requested donor information from groups seeking nonprofit status.

By the time this letter was sent, Shulman and Miller, who was the deputy IRS commissioner at the time, were aware of the extent of the targeting program for about a month.

Still, in a Sept. 11, 2012 response to the letter, Miller offered a broad interpretation of the law allowing the request for donor information and said nothing about the targeting practice.