Six candidates have been approved by Iran's theocracy to run in Friday’s presidential election to replace the late President Ebrahim Raisi, who died in a helicopter crash with several other officials in May.

Among them, Iran’s parliament speaker stands out as the most recognizable figure. A little-known politician and heart surgeon is also on the ballot. He is the only reformist while the others are more skewed toward hard-liners who back Supreme Leader Ayatollah Ali Khamenei without question and challenge the West.

And if previous elections are a guide to Iranian politics, several candidates could drop out in the final days before the vote to coalesce around a unity candidate.

On Tuesday, Khamenei called for “maximum” voter turnout in the election, which analysts say could support the reformist candidate. A parliamentary election in Iran earlier this year saw the lowest turnout since the country's 1979 Islamic Revolution.

Here's a look at the candidates:

Amirhossein Ghazizadeh Hashemi

Ghazizadeh Hashemi, 53, served as one of Raisi’s vice presidents and as the head of the Foundation of Martyrs and Veterans Affairs. He ran in the 2021 presidential election and received just under 1 million votes, coming in last place. In debates so far, he's urged the country to continue to follow the policies of Raisi and insisted that Iran does not need foreign investment to succeed, despite the widespread economic challenges the nation now faces.

Saeed Jalili

The 58-year-old Jaili is a hard-line politician and former senior nuclear negotiator. He ran in Iran's 2013 presidential election and registered in 2021 before withdrawing to support Raisi. Current CIA director Bill Burns, who dealt with Jalili in negotiations in the past, has described him as “stupefyingly opaque” in talks. He got the nickname “The Living Martyr” after losing a leg in the 1980s Iran-Iraq war. He maintains that Iran doesn't need to negotiate over its nuclear program with the West. Though he is seen as maintaining close ties to Khamenei, he's not considered to be a front-runner. His campaign largely has focused on rural voters.

Masoud Pezeshkian

A 69-year-old heart surgeon, Pezeshkian is the only reformist candidate among the hard-line figures seeking the presidency. He's said he'd want to renegotiate with the West to try and restart some version of the 2015 nuclear deal. He's put the need for the deal in economic terms, saying Iran needs to communicate with the world. Iran's former Foreign Minister Mohammad Javad Zarif, who served under the relative-moderate President Hassan Rouhani and helped strike the nuclear deal, has backed him. However, analysts believe Pezeshkian would need a heavy turnout to win — which is unlikely, given the current apathy gripping the nation. His campaign has so far focused on the youth vote, women and Iran's ethnic minorities.

Mostafa Pourmohammadi

Pourmohammadi, 64, is the only Shiite cleric running in the election. He served as interior minister under hard-line President Mahmoud Ahmadinejad and later as justice minister under Rouhani. In 2006, the United States State Department referred to Pourmohammadi as a “notorious human rights violator” for a leading role in the 1988 mass execution of several thousand political prisoners at Tehran's notorious Evin prison. The State Department also linked him to the so-called “chain murders” of activists and others in the 1990s. He's insisted the next president must deal with the world and criticized Iran's arming of Russia in the war in Ukraine — not because of the killing of civilians, but because he felt Tehran wasn't getting enough back from Moscow for its support. His campaign likely is counting on the backing of clerics and traditionalists.

Mohammad Bagher Qalibaf

The Iranian parliament speaker, Qalibaf, 62, is the highest-ranking official within the theocracy to be seeking the presidency. Analysts suggest he's the front-runner in the campaign, with Jalili as a second. Qalibaf is a former Tehran mayor with close ties to the country’s paramilitary Revolutionary Guard. Many remember that Qalibaf — as a former Guard general — was part of a violent crackdown on Iranian university students in 1999. He also reportedly ordered live gunfire to be used against students in 2003 while serving as the country’s police chief. Qalibaf maintains that he, as a strong manager, can save Iran from the crisis, borrowing from recent comments made by Khamenei. Qalibaf has focused on the middle class, as well as promising more cash handouts for the poor.

Alireza Zakani

The current mayor of Tehran, Zakani, 58, withdrew from the 2021 presidential election to back Raisi. Zakani has said he believes Iran can neutralize the effects of international sanctions but should pursue a diplomatic solution. He is a hard-liner who has repeatedly criticized reformists and moderates within Iran's political system, wants to see Iran stop using the dollar as a benchmark currency, and has called for Iran to create more value-added products from its oil to boost revenue. He has promised free health care for women and old people, as well as cash payments to poor people and reviving Iran's currency, the rial. However, he's offered no details on how he plans to accomplish these goals.