Iran's president has died in a helicopter crash while in office | Here's what happens next

LONDON -- Once seen as a likely successor to Iran's Supreme Leader, President Ebrahim Raisi has died in office, leaving the Islamic Republic's hardline establishment facing an uncertain future.

An ultraconservative president, 63-year-old Raisi was killed Sunday, along with Foreign Minister Hossein Amir-Abdollahian and other high-ranking officials, in a helicopter crash in Iran's remote northwest. Their death comes at a delicate time for a country that faces unprecedented challenges at home and from abroad.

The Islamic Republic's economy remains crippled by American sanctions, its young population is becoming growingly restive, and the country faces increasingly belligerent adversaries in the Middle East and beyond.

Raisi's death will "trigger elections at a time when the IRI (Islamic Republic of Iran) is at the nadir of its legitimacy and zenith of its exclusionary policies," Ali Vaez, Iran Project Director at the International Crisis Group think tank, said on X.

Here's what comes next.

Who steps in as president?

Power has now been transferred to Mohammad Mokhber, who had served as Raisi's vice president and was on Monday approved as acting president by Supreme Leader Ayatollah Ali Khamenei, the final arbiter of domestic and foreign affairs in the Islamic Republic.

Not as well known as Raisi, Mokhber is "another administrator," Sanam Vakil, director of the Middle East and North Africa program at the Chatham House think tank in London, told CNN's Becky Anderson. "He is close to the IRGC, close to the levers of power," Vakil said, adding that he is likely to present a model of "business as usual" in the coming days.

But the country must, by law, hold elections within the next 50 days. Experts say that the elections are likely to be hastily organized, with poor voter participation. In March, Iran recorded its lowest electoral turnout since the Islamic Republic's founding in 1979, despite government efforts to rally voters ahead of the ballot.

That vote - for seats in the parliament, or Majles, and the 88-member Assembly of Experts, which is tasked with picking the Supreme Leader - brought in mostly hardline politicians.

"The population has by and large lost faith in the idea that change can come through the ballot box," Trita Parsi, co-founder and Executive Vice President of the Quincy Institute for Responsible Statecraft in Washington, DC, wrote Sunday on X.

The March election also barred more moderate politicians from running - including former President Hassan Rouhani, once a regime stalwart - tightening the small circle of hardliners to continue the Supreme Leader's conservative rule after he dies.

"Real alternatives to Iran's hardliners have simply not been allowed to stand for office in the last few elections," Parsi said on X, adding that "those alternatives have in the eyes of the majority of the population lost credibility anyways, due to the failure to deliver change."

Until the Supreme Leader is replaced, however, little change is expected to follow Raisi's death, particularly on foreign policy.

"It is really the Supreme Leader and the Revolutionary Guards who make the final decisions, and even in the region mostly implement Iran's regional policy," Vaez said, adding that "overall we will see more continuity than change."

What are the longer-term implications of Raisi's death?

Raisi's death has raised questions about who will eventually succeed Iran's 85-year-old Supreme Leader Ayatollah Ali Khamenei, the most powerful man in the country.

The Iranian clerical establishment had invested heavily in Raisi during his presidency, seeing him as a potential successor to Khamenei. Observers say he had been groomed to be elevated to the Supreme Leader's position.

Raisi's death will create "a succession crisis in Iran," Karim Sadjadpour, a senior fellow at the Carnegie Endowment for International Peace, wrote on X.

The late president upheld some of the regime's most hardline policies, quashing the 2022 mass protests that sought to challenge repressive laws, such as the compulsory hijab.

According to the constitution, the 88-member Assembly of Experts picks the successor to the Supreme Leader after his death. Members of the Assembly itself are, however, pre-vetted by Iran's Guardian Council, a powerful 12-member body charged with overseeing elections and legislation.

The Assembly of Experts has become increasingly hardline over the years. In the March vote, Raisi was re-elected to the assembly, and the Guardian Council barred Rouhani from contesting a seat.

While there are procedures to selecting the Supreme Leader, discussions about successions are always "very opaque," Vakil said, adding that they take place "within a very close circle of individuals."

Some have pointed to the incumbent Supreme Leader's son Mojtaba Khamenei, a midlevel cleric, as a potential contender for the top post, but that would be a shift from the principles of the Islamic Republic, which overthrew a repressive monarchy in 1970 and has prided itself for shaking off hereditary rule.

Allowing Mojtaba to replace his father may, however, spur theories that Raisi's death was not accidental, Sadjadpour said.

Raisi's rivals are also likely to try to fill the vacuum he leaves, Vaez said.

"(This) definitely throws all the plans that offices of the Supreme Leader probably had out the window," Vaez told CNN's Paula Newton.

He added, however, that Iran has no shortage of political actors who are "subservient and belong to the old guard of the Islamic Republic" who can replace Raisi.

How will it impact Iran's foreign relations?

Raisi and Amir-Abdollahian oversaw a turnaround in Iran's relations with its Arab neighbors, helping normalized relations with longtime foe Saudi Arabia, with China's assistance. But they also saw the Islamic Republic initiate a large-scale direct attack on Israel for the first time, after a suspected Israeli attack on an Iranian diplomatic compound in Syria. That prompted Israel to launch an unprecedented retaliation, bringing the shadow war between the two nations out into the open.

Experts say that Raisi's death is unlikely to have an impact on the regime's foreign policy, which is almost exclusively the domain of the Supreme Leader.

Iran's foreign policy is decided by the Supreme National Security Council and can be vetoed by the Supreme Leader, Mohammad Ali Shabani, Iran expert and editor of the Amwaj.media news outlet, told CNN's Anderson. "We will see continuity in terms of how Iran approaches the regional files, collaboration with regional allies."

He added that a similar trajectory is likely to be seen on the nuclear program.

Could the upcoming presidential election bring change to Iran?

Some experts say that the election presents an opportunity for the regime to bring back sidelined moderates. While Khamenei is likely to maintain conservative rule, he "has always emphasized voter turnout as a litmus test of the legitimacy of the system," Shabani said. "That election can be a watershed moment for Iran."

Raisi came to power in elections that many Iranians saw as a foregone conclusion. With moderate candidates squeezed out, voter turnout was extremely low, highlighting the regime's waning legitimacy.

"If the Supreme Leader chooses to use these early elections as a watershed moment to open up the political space, to get people to vote again, that could be a massive gamechanger," Shabani said, adding that this would also impact succession to the Supreme Leader.

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