Replacing Iran’s top national security official Ali Larijani after he was killed in an Israeli strike on Tuesday won’t be an easy task.

The veteran politician was regarded by many analysts as the most important decision-maker in the country, a skilled negotiator who could work across different camps within the regime and internationally.

By law, Iranian President Masoud Pezeshkian will be the one to appoint the next national security advisor and speculation is swirling that influential regime figure Saeed Jalili may step into the role.

Analysts say there is strong precedence for the job going to one of the Supreme Leader’s representatives to the National Security Council. Larijani’s death leaves Jalili as a likely option – he has previously served as national security advisor, was a chief nuclear negotiator and is a current member of the Expediency Discernment Council.

“Jalili is an arch-hardliner, leader of the most vociferously anti-Western and extremist section of the regime,” said Iran analyst and author Arash Azizi, who is also a lecturer and historian at Yale University.

Jalili, however, may be less skilled at working within the various parts of the system as Larijani was.

“His rigidity and extremism might become a vulnerability for the regime and lessen its ability to manuvere the dire straits it is in,” Azizi said.

The elite Revolutionary Guards “hold much of the real power in Iran today” and so may want someone with “more military experience who could be more suited for the current moment,” Azizi added.

Whoever is chosen as Larijani’s replacement will have a major role in any negotiations to end the war.

Following Larijani’s death, Jalili posted a message saying, “these actions will not rescue the feeble enemy from the quagmire in which it is trapped; rather, they will accelerate the course of its defeat and humiliation,” the state-affiliated Tasnim news agency reported.