(CNN) — Prosecutors in the Georgia election subversion case against former President Donald Trump have officially listed former Vice President Mike Pence as one of the witnesses who could be called to testify at trial, according to multiple sources familiar with court documents that remain under seal.

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Pence, who has appeared before a federal grand jury as part of special counsel Jack Smith’s probe into Trump’s efforts to overturn the 2020 election, has not been considered a major part of criminal proceedings in Georgia.

Witness lists submitted by Fulton County prosecutors have not been made public and remain tightly held. Sources told CNN that the most recent version of the witness list, which was produced by prosecutors just days ago, included upward of 150 names. Among them is Pence.

Pence could become a key witness as one of the few one-time Republican allies of the former president to strongly rebuke Trump’s claims of widespread voter fraud in the Peach State.

“Despite what the former president and his allies have said for now more than two and a half years and continue to insist … the Georgia election was not stolen, and I had no right to overturn the election on January 6,” Pence said at the National Conference of State Legislatures after Trump was indicted in August.

Unlike in the federal probe, Pence has not testified under oath as part of the Georgia case – including before the special purpose grand jury that interviewed 75 witnesses in its investigation.

A spokesperson for Pence declined to comment on the Georgia case.

Pence’s name appearing on the witness list in Georgia, which has not been previously reported, is the first concrete sign that the Fulton County district attorney’s office is preparing to put him on the stand. Pence has already signaled a willingness to testify as a witness in any federal trial.

In an interview with CNN this summer, Pence said he would comply with the law if he were compelled to testify in the federal case. “I have no plans to testify, but, look, we’ll always comply with the law,” he said, noting there are “profound” First Amendment issues that will be litigated in that case.

Fifteen defendants remain in the sprawling racketeering case. So far, four of Trump’s co-defendants – including three of his former attorneys – have already cut deals with prosecutors to plead guilty and testify in the case.

A spokesperson with the Fulton County District Attorney’s office told CNN they cannot comment on potential witnesses at this phase of the case.

The former vice president was publicly pressured by then-President Trump to overturn the 2020 presidential election results during the federal certification of votes on Jan. 6, 2021.

On Friday, Trump’s lead counsel in the Georgia case, Steve Sadow, indicated he believes the DA’s office may attempt to call Pence as a witness. He made the revelation as he pushed for access to documents and materials in the hands of special counsel Jack Smith, which may be relevant to the separate state case in Georgia.

Sadow argued that Trump’s federal case in Washington, D.C., is largely “a mirror image” to his case in Fulton County and therefore he needs a list of evidence from that case.

“This is a problem,” Sadow argued.

“There is no doubt that the special counsel’s office … has relevant and material information that deals with the allegations in this case,” Sadow said in court.

Specifically, Sadow referenced contemporaneous notes that were taken by Pence after the 2020 election and obtained by Smith’s team from the National Archives. However, those notes are not in the possession of Trump’s Georgia team or the district attorney’s office despite potentially being material to their case – particularly if Pence is called to testify.

Fulton County Superior Court Judge Scott McAfee agreed there was a “great deal” of overlap in the two cases and said Georgia prosecutors should consider reaching out to special counsel Smith to coordinate on discovery issues.

Sadow wrote in a previous court filing that he reached out to Trump’s lawyers in the federal case, but they told him that there’s a court order prohibiting them from sharing materials with people who aren’t directly involved in that case. So, Sadow proposed that Fulton County prosecutors reach out to Smith’s team and the federal judge in DC “to determine if suitable arrangements can be made” to hand over the materials.

Fulton County prosecutor Nathan Wade suggested at Friday’s hearing that Sadow subpoena the Justice Department for the federal discovery, and Sadow said he would “prepare” a subpoena that he’ll send to Smith’s team.

These questions about overlapping discovery speak to the challenging dynamic of Trump facing criminal charges in both state and federal court for many of the same actions he took to overturn his 2020 defeat.

CNN’s Evan Perez contributed to this report.