A federal judge on Monday said U.S. Sen. Lindsey Graham must testify before a special grand jury in Atlanta that is investigating whether then-President Donald Trump and his allies broke any laws while trying to overturn his narrow 2020 general election loss in the state.

Attorneys for Graham, R-S.C., had argued that his position as a U.S. senator provided him immunity from having to appear before the investigative panel and asked the judge to quash his subpoena. But U.S. District Judge Leigh Martin May wrote in an order Monday that immunities related to his role as a senator do not protect him from having to testify. Graham’s subpoena instructs him to appear before the special grand jury on Aug. 23, but his office said Monday he plans to appeal to the 11th U.S. Circuit Court of Appeals.

Fulton County District Attorney Fani Willis opened the investigation last year, and a special grand jury with subpoena power was seated at her request this year. Last month she filed petitions seeking to compel testimony from seven Trump advisers and associates.

Prosecutors have indicated they want to ask Graham about phone calls they say he made to Georgia Secretary of State Brad Raffensperger and his staff in the weeks following Trump’s election loss to Democrat Joe Biden.

Graham had argued that a provision of the Constitution provides absolute protection against a senator being questioned about legislative acts. But the judge found there are “considerable areas of potential grand jury inquiry” that fall outside that provision’s scope. The judge also rejected Graham’s argument that the principle of “sovereign immunity” protects a senator from being summoned by a state prosecutor.

Graham also argued that Willis, a Democrat, had not demonstrated extraordinary circumstances necessary to compel testimony from a high-ranking official. But the judge disagreed, finding that Willis has shown “extraordinary circumstances and a special need” for Graham’s testimony on issues related to an alleged attempt to influence or disrupt the election in Georgia.

May, the judge, last month rejected a similar attempt by U.S. Rep. Jody Hice, R-Ga., to avoid testifying before the special grand jury. Former New York mayor and Trump attorney Rudy Giuliani had argued he couldn’t travel to Atlanta to testify because of health issues, but Fulton County Superior Court Judge Robert McBurney, who’s overseeing the special grand jury, instructed him to appear on Wednesday.

Graham’s office said in a statement Monday that the senator disagrees with the judge’s interpretation of the provision of the Constitution he believes protects him from being questioned by a state official. His lawyers have said that he was making inquiries that were clearly part of his legislative duties, related to certification of the vote and to the proposal of election-related legislation.

But the judge wrote that that ignores “the fact that individuals on the calls have publicly suggested that Senator Graham was not simply engaged in legislative factfinding but was instead suggesting or implying that Georgia election officials change their processes or otherwise potentially alter the state’s results.”

In calls made shortly after the 2020 general election, Graham “questioned Secretary Raffensperger and his staff about reexamining certain absentee ballots cast in Georgia in order to explore the possibility of a more favorable outcome for former President Donald Trump,” Willis wrote in a petition.

Graham also “made reference to allegations of widespread voter fraud in the November 2020 election in Georgia, consistent with public statements made by known affiliates of the Trump Campaign,” she wrote.

Republican and Democratic state election officials across the country, courts and even Trump’s attorney general found there was no evidence of any voter fraud sufficient to affect the outcome of his 2020 presidential election loss.

Trump-allied lawmakers were planning to challenge the tallies from several battleground states when Congress convened on Jan. 6, 2021, to certify the results under the Electoral Count Act, but after the Capitol attack that day Georgia’s tally was never contested.

Willis has confirmed that the investigation’s scope includes a Jan. 2, 2021, phone call between Trump and Raffensperger during which Trump urged Raffensperger to “find” enough votes to overturn his loss in Georgia.

“I just want to find 11,780 votes, which is one more than we have,” Trump said during that call.

Trump has denied any wrongdoing and has described his call to Raffensperger as “perfect.”