Sen. Lindsey Graham (R-S.C.) on Friday asked the Supreme Court to shield him from testifying in an investigation into former President Trump’s alleged interference in the 2020 election in Georgia.

Graham’s request comes a day after a lower appeals court refused to halt his testimony before a Fulton County, Ga., special grand jury.

In court papers filed Friday to Justice Clarence Thomas, who handles emergency matters arising from the U.S. Court of Appeals for the 11th Circuit, Graham urged the court to find that constitutional protections for lawmakers should prevent him from being forced to comply with a subpoena issued by District Attorney Fani Willis (D).

“Without a stay, Senator Lindsey Graham will soon be questioned by a local Georgia prosecutor and her ad hoc investigative body about his protected ‘Speech or Debate’ related to the 2020 election,” Graham’s lawyers wrote. “This will occur despite the Constitution’s command that Senators ‘shall not be questioned’ about ‘any Speech or Debate.’”

Graham has asked the court block his subpoena to allow an appeal to play out.

Graham’s appeal concerns a federal judge’s ruling that the senator could avoid testifying only to the extent that it concerned calls he made to state election officials related to fact-finding for his own vote on certifying of the 2020 election — but that questioning could otherwise proceed.

Graham has said the arrangement will permit investigators “backdoor ways” to ask him about the calls.

On Thursday, a unanimous three-judge panel on the 11th Circuit rebuffed the South Carolina Republican, finding that, “Senator Graham has failed to demonstrate that he is likely to succeed on the merits of his appeal.”

Graham is among several high-profile figures whom Willis has pursued as part of her probe. She has also subpoenaed a group of Republicans who served as a phony slate of pro-Trump electors in 2020.

Trump’s effort to bypass the will of voters in Georgia and a handful of other swing states he lost to President Biden in the 2020 election sparked congressional investigations and figure into multiple criminal probes, including by the Department of Justice and the Fulton County district attorney.

—Updated at 6:14 p.m.