Iran’s leaders are scrambling to replace Supreme Leader Ayatollah Ali Khamenei, who ruled the country with an iron grip for 37 years before he was killed in the surprise U.S. and Israeli bombardment on Saturday.

It’s only the second time since the 1979 Islamic Revolution that a new supreme leader is being chosen. Potential candidates range from hard-liners committed to confrontation with the West to reformists who seek diplomatic engagement.

Iran’s Supreme Leader has the final say on all major decisions, including war, peace and the country’s disputed nuclear program.

In the meantime, a provisional governing council composed of President Masoud Pezeshkian, hard-line judiciary chief Gholamhossein Mohseni Ejei and senior Shiite cleric Ayatollah Ali Reza Arafi is guiding the country through its biggest crisis in decades. Foreign Minister Abbas Araghchi said Sunday that a new Supreme Leader would be chosen early this week.

Here are the top contenders.

Mojtaba Khamenei
The son of Khamenei, a mid-level Shiite cleric, is widely considered a potential successor. He has strong ties to Iran’s paramilitary Revolutionary Guard but has never held office. His selection could prove awkward, as the Islamic Republic has long criticized hereditary rule and cast itself as a more just alternative.

Ayatollah Ali Reza Arafi
Arafi is a member of the provisional government council. Khamenei selected the senior Shiite cleric to the Guardian Council in 2019, and three years later, he was elected to the Assembly of Experts. He leads a network of seminaries.

Hassan Rouhani
Rouhani, a relative moderate, was president of Iran from 2013 to 2021 and reached the landmark nuclear agreement with the Obama administration that U.S. President Donald Trump scrapped during his first term.

Hassan Khomeini
Khomeini is the most prominent grandson of the founder of the Islamic Republic, Ayatollah Ruhollah Khomeini. He is also seen as a relative moderate, but he has never held government office.

Ayatollah Mohammed Mehdi Mirbagheri
Mirbagheri is a senior cleric popular with hard-liners who serves on the Assembly of Experts. He is currently the head of the Islamic Cultural Center in Qom, the main center for Islam.