Iranians will vote for a new president on Friday following Ebrahim Raisi's death in a helicopter crash, choosing from a tightly controlled group of four candidates loyal to the supreme leader, at a time of growing public frustration.
While the election is unlikely to bring a major shift in the Islamic Republic's policies, the outcome could influence the succession to Ayatollah Ali Khamenei, Iran's 85-year-old supreme leader, in power for three-and-a-half decades.
Khamenei has called for a "maximum" turnout to offset a legitimacy crisis fuelled by public discontent over economic hardship and curbs on political and social freedoms.
Voter turnout has plunged over the past four years, with a mostly young population chafing at political and social restrictions.
Polls open at 8:00 am local time (0430 GMT) and close at 6:00 pm (1430 pm GMT), but are usually extended until as late as midnight. As ballots are counted manually, the final result is expected to be announced only in two days although initial figures may come out sooner.
If no candidate wins at least 50 percent plus one vote from all ballots cast including blank votes, a run-off round between the top two candidates is held on the first Friday after the election result is declared.
Three of the candidates are hardliners and one a low-profile comparative moderate, backed by the reformist faction that has largely been sidelined in Iran in recent years.
Critics of Iran's clerical rule say the low and declining turnout of recent elections shows the system's legitimacy has eroded. Just 48% of voters participated in the 2021 election that brought Raisi to power, and turnout hit a record low of 41% in a parliamentary election three months ago.
The election now coincides with escalating regional tensions due to war between Israel and Iranian allies Hamas in Gaza and Hezbollah in Lebanon, as well as increased Western pressure on Iran over its fast-advancing nuclear programme.
The next president is not expected to produce any major policy shift on Iran's nuclear programme or support for militia groups across the Middle East, since Khamenei calls all the shots on top state matters. However, the president runs the government day-to-day and can influence the tone of Iran's foreign and domestic policy.
A hardline watchdog body made up of six clerics and six jurists aligned with Khamenei vets candidates. It approved just six candidates from an initial pool of 80. Two hardline candidates subsequently dropped out.
Prominent among the remaining hardliners are Mohammad Baqer Qalibaf, parliament speaker and former commander of the powerful Revolutionary Guards, and Saeed Jalili, a former nuclear negotiator who served for four years in Khamenei's office.
The sole comparative moderate, Massoud Pezeshkian, is faithful to the country's theocratic rule but advocates detente with the West, economic reform, social liberalisation and political pluralism.
His chances hinge on reviving the enthusiasm of reform-minded voters who have largely stayed away from the polls for the last four years after previous pragmatist presidents achieved little change. He could also benefit from his rivals' failure to consolidate the hardline vote.
All four candidates have vowed to revive the flagging economy, beset by mismanagement, state corruption and sanctions reimposed since 2018 after the U.S. ditched Tehran's 2015 nuclear pact with six world powers.
The hashtag #ElectionCircus has been widely posted on social media platform X by Iranians in the past few weeks, with some activists at home and abroad calling for an election boycott, arguing that a high turnout would legitimise the Islamic Republic.
