The chairman of the Senate Judiciary Committee has invited special counsel Robert Mueller III to testify before the panel about his conversations with U.S. Attorney General William Barr.

Sen. Lindsey Graham, R-South Carolina, wrote to Mueller on Friday to invite him to clear up whether Barr misrepresented the substance of his March 27 phone call with the special counsel. Barr, in testimony this week before the Senate, told lawmakers that the conversation centered around Mueller’s request for the prompt release of the summaries of his findings. The attorney general disputed claims that Mueller was frustrated by Barr’s rollout of the findings.