Elham said Larijani might join the delegation. A Supreme National Security Council official said the post would be permanently filled within days.
Some analysts pointed out that style rather than substance characterized the differences between the two camps on the nuclear issue.
"Larijani was not advocating making major nuclear compromises, but he appreciated the need to retain constructive dialogue with the EU and felt Ahmadinejad needlessly undermined Iran's case with his blusterous rhetoric," said Karim Sadjadpour, an Iran expert at the Carnegie Endowment for International Peace, a Washington think tank.
Replacing Larijani with Jalili buys Iran more time to pursue its ultimate goal of becoming a nuclear power, said Saeed Leylaz, an Iranian analyst and economist.
"The Islamic Republic of Iran is in a race against time with the West," Leylaz said. "All in all, Iran is going toward more radicalization and full nuclear power."