It’s the interviews by the FBI with him and Cheney in the Plame Affair, and Bush is insisting that it’s covered by executive privilige, and Mukasey going along with it.
Simply put, enough is enough. Find Mukasey in contempt, and have the sergeant at arms of the Congress throw his ass in th t cell in the basement of Congress.
While you are at it, get Miers and Bolton in a cell.