U.S. Attorney General William Barr can be expected to face questions Wednesday from members of the U.S. Senate Judiciary Committee about the nature and scope of his communication with Robert Mueller III, the special counsel who was appointed to lead the Russia investigation.

Mueller was frustrated about how Barr in late March portrayed the “principal conclusions” of the report, which was released in redacted form last month. In a letter to Barr on March 27, the substance of which was released late Tuesday, Mueller said the attorney general’s four-page summary “did not fully capture the context, nature, and substance of this office’s work and conclusions.”