Iranians vote in a presidential election on Friday that is forecast to cement regime hardliners’ control over the Islamic republic, but any victory for the conservatives risks being marred by the lowest turnout since the 1979 revolution.

The crucial polls take place as the Biden administration seeks to de-escalate tensions in the region and revive the nuclear deal Tehran signed with world powers.

Ebrahim Raisi, a cleric who heads the judiciary, is the frontrunner after the authorities banned leading reform candidates and Ali Larijani, a prominent conservative who helped negotiate the 2015 nuclear accord, from participating.

Raisi has a healthy lead over his main rivals: Abdolnaser Hemmati, who was central bank governor before announcing his candidacy as the main reformist candidate, and Mohsen Rezaei, another senior conservative, according to local polls.

But even if one of the hardline candidates wins, a low turnout would undermine the victory and damage the regime’s claims that the elections provide popular legitimacy in a region where few votes are held.

“I will not vote, nor will any of my close relatives,” said Ali, a 36-year-old engineer and musician. “If our votes could have changed anything, the regime would not have let us cast a vote. The whole voting is a show and the president’s share in decision making is less than 5 per cent.”

A hairdresser in a Tehran barber shop works, as the first presidential candidates’ TV debate is shown on TV in the background

Polls are predicting that turnout could fall below 50 per cent. The bleak mood, set against the backdrop of economic crisis and the coronavirus pandemic, is in stark contrast to the last election in 2017 when more than 70 per cent of eligible voters cast ballots to secure a second and final term for President Hassan Rouhani with a landslide victory.

That poll, in which Raisi came a distant second, was viewed as a referendum on the 2015 nuclear deal, which Rouhani promised to use to turn around the economy, attract foreign investment and step up engagement with the west.

But the expectations raised by his win were crushed after the then US president Donald Trump unilaterally withdrew the US from the pact in 2018 and imposed swingeing sanctions on the republic, plunging the economy into a deep recession.

The crisis severely undermined reformers who had backed Rouhani, a centrist, in the hope of securing change. But it emboldened hardliners who had warned the US could not be trusted.

President Joe Biden has said the US will rejoin the accord and lift many sanctions if Iran comes back into full compliance with the agreement. Iran is expected to continue negotiations with the remaining signatories to the deal — France, Germany, the UK, China and Russia — if Raisi wins, with hardliners keen to have sanctions lifted to ease pressure on the economy.

But after four years of tumult and economic hardship, many Iranians have given up any lingering hope that their votes can translate into change for the better. Instead, they believe the elections are used by the regime to validate its theocratic rule.

“Before the elections, all politicians plead to people to vote for Iran. The day after the elections, they say a high turnout is a victory of the Islamic republic,” said Aziz, a 68-year-old manager of a private company. “I’m not going to feed that propaganda ever again.”

Iranians sit at a sidewalk cafe in northern Tehran

Ayatollah Ali Khamenei, the supreme leader, on Wednesday warned Iranians that foreign pressure on the country could increase if the turnout was low.

“It is true that we think military, political and economic means strengthen our power, but none are as important as people’s presence [in elections],” he said. The top leader urged Iranians from all political inclinations to go to the polls because the country needed them.

Low turnout, a rare act of civil disobedience by voters, is likely to favour Raisi, analysts say, as he has a core constituency of conservative voters who are expected to cast their ballots.

Hosna, a 30-year-old photographer, said Raisi was the “most honest candidate who is favoured by the supreme leader”, adding: “He can clean up the mess we are inheriting from the Rouhani government. It is our religious duty to vote as said by the supreme leader.”

But many people assume hardliners in power centres such as the elite Revolutionary Guards, the judiciary and Khamenei’s office have already decided who should be the next president.

The best hope for Hemmati, the sole reformist candidate, is that no candidate secures 50 per cent of the vote, so forcing a run-off.

His chances have been hindered by splits among prominent reformists over whether it is worth voting at all. Some have used social media to urge people to cast their ballots, using the hashtag “turn the tables”. But other reformists believe it is an unfair contest and say there is no point.

Many voters agree. “Enough is enough. I will not vote ever again,” said Mehran, a 52-year-old teacher. “Reformists have cheated us again and again by saying that reform is possible through the ballot box. Nothing is going to change ever.”