Atlanta-area prosecutors have indicated that they will go before a grand jury early next week to present the results of their investigation into election interference by former President Donald J. Trump and his allies, raising the possibility that within days Mr. Trump could face a fourth criminal indictment.

On Saturday, two witnesses who have received subpoenas to testify before the grand jury — Geoff Duncan, the former lieutenant governor of Georgia, and George Chidi, an independent journalist — revealed that they had received notices to appear before the grand jury on Tuesday. A spokesperson for the Fulton County district attorney’s office, which conducted the investigation, could not be reached for comment on Saturday.

A state-level indictment of Mr. Trump in Georgia would follow closely on the heels of a federal indictment, unveiled this month, that is also related to the former president’s attempts to overturn the results of the 2020 election. But unlike with federal convictions, Mr. Trump, if re-elected president, could not attempt to pardon himself if convicted of state crimes in Georgia.

Moreover, while the federal case brought by the special counsel Jack Smith names only Mr. Trump, details have surfaced suggesting that a Georgia indictment could name numerous people, some of them well known and powerful, who played roles in the multipronged effort to help Mr. Trump overturn his narrow 2020 election loss in the state.

Mr. Chidi informed The New York Times on Saturday that he had received the notice to appear. Mr. Duncan on Saturday told CNN, where he is an on-air contributor, that he had received the notice to appear.