ATLANTA (AP) — A federal judge says U.S. Sen. Lindsey Graham must testify before a special grand jury in Atlanta.

The panel is investigating whether then-President Donald Trump and his allies broke any laws while trying to overturn his 2020 general election loss in the state.

Fulton County District Attorney Fani Willis opened the investigation last year.

A special grand jury with subpoena power was seated at Willis’ request.

Prosecutors have indicated they want to ask Graham about phone calls they say he made to Georgia’s secretary of state and his staff following the election.

Graham’s attorneys argued he had immunity from having to appear.

His office released a statement:

The Constitution’s Speech or Debate Clause prevents a local official from questioning a Senator about how that Senator did his job.  Here, Senator Graham was doing his due diligence before the Electoral Count Act certification vote — where he voted to certify the election.  Although the district court acknowledged that Speech or Debate may protect some of Senator Graham’s activities, she nevertheless ignored the constitutional text and binding Supreme Court precedent, so Senator Graham plans to appeal to the 11th Circuit.

Office of Senator Lindsey Graham

Graham must appear Aug. 23 and had no immediate comment Monday.