Gov. Brian Kemp will testify Tuesday morning before the Fulton County special grand jury examining whether former President Donald Trump and his allies criminally meddled in Georgia’s 2020 elections, according to two sources with knowledge of the appearance.

The Republican, who cruised to re-election last week, is among the most high-profile witnesses to testify before the 23-person grand jury. His blockbuster appearance represents a hard-fought victory for the Fulton County District Attorney’s office, which has been angling for Kemp’s testimony for a year-and-a-half.

Spokesmen for Kemp and DA Fani Willis declined to comment. The two sources who spoke with The Atlanta Journal-Constitution asked for anonymity because they were not authorized to speak on the record.

In late August, the governor had been directed by Fulton Superior Court Judge Robert McBurney to appear before the grand jury “some date soon after” the election.

Kemp is a central witness to the investigation, which Willis launched in Feb. 2021. The grand jury was seated in May to help her compile evidence and testimony.

In late 2020, Kemp faced a barrage of attacks from Trump and his allies after he refused their calls to illegally convene a special session of the state legislature to undo Democrat Joe Biden’s narrow victory in Georgia. Kemp said that state law barred him from “interfering.”

Kemp subsequently became a frequent punching bag at Trump rallies. The president said he was “ashamed” to have endorsed Kemp in 2018, and recruited former U.S. Sen. David Perdue to wage an ultimately doomed primary challenge against him.

Unlike Secretary of State Brad Raffensperger, whose Jan. 2, 2021 conversation with Trump was recorded, the details of Kemp’s behind-the-scenes interactions with the commander-in-chief are largely unknown.

Fulton prosecutors previously said they’re interested in questioning Kemp about the identities of the people who tried to get in touch with him following the 2020 elections; the contents of phone calls Kemp had with Trump or his associates; evidence the Trump campaign provided in support of its theory that Georgia’s election was rigged; whether Trump specifically sought a special election or other relief; and any threats that might have been made.

Kemp is “uniquely knowledgeable about the election interference matters being investigated by the grand jury since he was personally involved in the conversations at issue,” Nathan Wade, a special prosecutor advising the grand jury, said in an August court filing.

With his re-election campaign behind him — a victory he secured without Trump’s help — it’s possible Kemp could be more open to answering questions from jurors and prosecutors.

But there’s also a history of bad blood between Kemp’s camp and the Fulton DA’s office, which is advising the grand jury.

Kemp had initially cooperated voluntarily with the investigation, agreeing to a July 25 taped interview under oath.

But communications soured between his team and prosecutors over the summer, according to internal emails shared in August court filings. When the two sides couldn’t agree on ground rules for the interview, Kemp’s aides called it off, and the governor was subpoenaed shortly thereafter.

The day before Kemp was scheduled to appear before the grand jury on Aug. 18, the governor’s attorney moved to quash the subpoena, arguing that it was a politically-motivated summons designed to hurt Kemp less than 90 days before the election by Willis, a Democrat.

His counsel also argued that Kemp was shielded from testifying due to sovereign immunity, executive privilege and attorney-client privilege.

McBurney, who is overseeing the grand jury and has worked to insulate it from appearing overly partisan, rejected Kemp’s argument that he shouldn’t have to testify. But he said Kemp’s testimony could be delayed until after his rematch with Democratic rival Stacey Abrams.

McBurney also clarified in August that Kemp is facing no accusations of criminal activity as part of the investigation.

It’s rare for a sitting governor to be subpoenaed, particularly for a criminal investigation. But the grand jury has already heard from the state’s three other top GOP officials: Raffensperger, Lt. Gov. Geoff Duncan and Attorney General Chris Carr.

Earlier Monday, Carr and Kemp’s outside counsel, Brian F. McEvoy, had filed a motion under seal in Fulton Superior Court that contained “information sensitive to the Special Purpose Grand Jury’s ongoing investigation.”