The IG testified yesterday at a hearing by the House Oversight Committee. According to one news story:
The White House’s refusal to release communications related to the Fast and Furious gun-walking program and the refusal of a White House official to be interviewed about the matter “made it impossible” for the inspector general (IG) of the Justice Department to “pursue that aspect of the case,” the IG, Michael Horowitz, testified.
He added that the sought-after White House interview and communications constituted “a lead we wanted to follow.”
Now, the IG doesn't call it stonewalling but he wanted to pursue WH links and they declined interviews. I'll be interested to see if this angle interests any of the mainstream press.