Fulton County District Attorney Fani Willis, who has been investigating election interference in the state since early last year, requested the grand jury in January to allow her to issue subpoenas to those who have refused to cooperate otherwise.
“I just want to find 11,780 votes, which is one more than we have,” Mr Trump said during the conversation.
Investigators are also examining a November 2020 phone call between Senator Lindsey Graham and Mr Raffensperger, the abrupt resignation of the US Attorney in Atlanta on 4 January 2021, and comments made during December 2020 Georgia legislative committee hearings on the election.
Former US Attorney Michael Moore told CNN the grand jury would be looking closely at whether those conversations met the legal definition of crimes including electoral fraud.
“You are really talking about election fraud, a conspiracy to commit election fraud, was there a solicitation to commit election fraud or maybe was there an effort to interfere with the performance of the secretary of state’s official duties.”
“So those things may have tentacles,” he added. “This may become a little bit like an octopus of an investigation. Some evidence may be developed that they decide that they want to pursue a little bit further.”
The chief judge ordered the special grand jury to be seated for a period of up to a year, beginning Monday. It will be made up of 16 to 23 people called from the county master jury list.
Special grand juries focus on investigating a single topic and making recommendations to the district attorney, who then decides whether to seek an indictment from a regular grand jury.
Because of the intense public interest in this case, the court has made arrangements for at least parts of the special grand jury seating process to be broadcast to the news media and public. Once the special grand jury is seated, however, everything it does will happen in secret.
Since Mr Trump’s unsuccessful attempts to reverse the results of the 2020 election, he has endorsed secretaries of state in several battleground states who are sympathetic to his views.
Mr Trump has endorsed Jody Hice, Mr Raffensburger’s primary opponent, for the Georgia Secretary of State race.
Dozens of court cases found no merit to his claims that votes in six swing states were fraudulent.
Associated Press contributed to this report
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