A federal judge on Friday denied a request from Sen. Lindsey Graham, R-S.C., to delay his scheduled testimony before a special grand jury in Fulton County, Georgia, as part of an investigation of possible interference in the state’s 2020 election by former President Donald Trump and his allies.

The ruling came four days after Judge Leigh Martin May rejected Graham’s bid to entirely quash a court-ordered subpoena for his testimony as a witness in the probe. Graham is currently scheduled to testify before the grand jury next Tuesday.

The senator had asked the judge to temporarily halt the enforcement of the subpoena, pending his appeal of Monday’s ruling trying to entirely quash the subpoena and get out of testifying. The U.S. Court of Appeals for the Eleventh Circuit received Graham’s appeal on Thursday.

Fulton County District Attorney Fani Willis, who is conducting the probe, wants to question Graham about phone calls he made to Georgia Secretary of State Brad Raffensperger and his staff after the November 2020 election. Raffensperger reportedly said at that time that Graham had questioned him about Georgia’s election laws, including whether the secretary had the power to toss out certain mail ballots.

Trump, who falsely blames widespread fraud for his loss to President Joe Biden, called Raffensperger days before Congress convened to confirm the election results and urged him to “find” enough votes to change the outcome of Georgia’s contest.

Lawyers for Graham, a close ally of Trump’s, had argued to May that the calls were “quintessentially legislative factfinding” by a sitting U.S. senator, and as such are protected by the speech and debate clause of the Constitution.