Iranian President Ebrahim Raisi has died in a helicopter crash with his Foreign Minister Hossein Amir-Abdollahian.
Mr Raisi, 63, rose to power in 2021, taking over as president from Hassan Rouhani.
Trita Parsi, executive vice-president of the Quincy Institute for Responsible Statecraft, and Al Jazeera investigative reporter Soraya Lennie explain what happens now.
What was next for Raisi?
Mr Raisi was expected to become Iran's next supreme leader.
Dr Parsi told RN Breakfast this was predicted to happen in the next few years.
"It's likely because of that, this election will be impactful," Dr Parsi said.
The current supreme leader is Ali Khamenei, who has been the second supreme leader of Iran since 1989.
This followed his own presidency between 1981 and 1989. He is 85 years old.
Who is in charge in the interim?
The country's first vice-president, Mohammad Mokhber, takes over, with the confirmation of the supreme leader, who has the final say in all matters of state.
Mr Mokhber, like Mr Raisi, is seen as being close to the supreme leader. He became first vice-president in 2021 when Mr Raisi was elected president.
From here, a council consisting of the first vice-president, the speaker of parliament and the head of the judiciary must arrange an election for a new president.
When do they have an election?
The election must occur within 50 days.
Dr Parsi said this situation was "unprecedented" in Iran.
"This is the first time a sitting president has died," he said.
Before Mr Raisi's death, the next presidential election was due to take place in 2025.
"It comes at a very bad time for the government," Dr Parsi said.
"The government is unpopular, enthusiasm amongst the population is at a record low."
And considering what happened in the 2021 election, Dr Parsi predicts this one will have a low turnout.
What happened in the last election?
The vast majority of Iranians boycotted the election. Dr Parsi said across the nation only about 40 per cent of voters participated, and in the capital Tehran, only seven per cent went to the ballots.
"The trend for the last decade is the hard-liners have shrunk the political spectrum in Iran," Dr Parsi said.
"More and more members of parliament are not allowed to run for re-election ... they’re considered not being loyal to the system."
He said hardly any reformist or centrist were allowed to run, which resulted in the 2021 boycott.
"[Mr Raisi] wields power not just because of this, but because of his lineage and his backing through particular elements within the establishment, very hard-line backing," Ms Lennie told News Channel.
"They now basically control the judiciary, the executive branch parliament as well as the unified establishment at the moment."
She said Mr Raisi along with Mr Amir-Abdollahian were two of Iran's most important political figures.
What does it mean for the US?
Dr Parsi said it was not the death of the president that would have an impact, but rather if it leads to a debilitating crisis inside Iran.
"That could have a negative impact on the US standpoint," he said.
"There is an uneasy truce between the US and these militias the Iranians have supported in Iraq and Syria."
He said Iran had been able to influence these militias to pull back on attacking US troops and if there is an internal crisis the nation may lose influence.
However, Ms Lennie said in terms of foreign policy, there was a consistent undercurrent that continues despite changes in power.
"Policies regarding, for example, Israel, don't change, that doesn't change," she said.
"Iran doesn't recognise Israel and it never has. Since the revolution in 1979, and that will continue.
"Iran's support of groups like Hezbollah and Hamas is also not a question. Its ties to countries like Lebanon, Iraq, and Syria are important regional allies, also not going to change.
"The foreign policy within the region will remain consistent."
ABC/Wires
