The House’s chief investigative committee on Tuesday accused the IRS of stonewalling its probe into the agency's unfair targeting of Tea Party groups and other politically-affiliated organizations, saying Congress has received only a fraction of the documents it requested and many of those are useless.

The House Oversight and Government Affairs Committee letter directly blames acting Commissioner Danny Werfel for the “systematic manner” in which his agency has “attempted to delay, frustrate, impede and obstruct” the committee’s investigation, despite his promising just weeks earlier to fully cooperate.