DUBAI: Iranians choose a president on Friday in a contest likely to be won by a judge fiercely loyal to the religious establishment, although large numbers of people are expected to ignore the vote due to discontent with economic hardship and hardline rule.

With uncertainty surrounding Iran's efforts to revive its 2015 nuclear deal, and growing poverty at home after years of U.S. sanctions, voter turnout is seen by Iranian analysts as a referendum on the leadership's handing of an array of crises.

Hardliner Ebrahim Raisi, 60, a close ally of Supreme Leader Ayatollah Ali Khamenei, is favourite to succeed the incumbent Hassan Rouhani, forbidden under the constitution from serving a third four-year term.

A win for the Shi'ite cleric would confirm the political demise of pragmatist politicians like Rouhani, weakened by Washington's decision to quit the nuclear deal and reimpose sanctions in a move that stifled rapprochement with the West.

But it would not disrupt Iran's bid to revive the agreement and break free of tough oil and financial sanctions, Iranian officials say, with the country's ruling clerics aware their political fortunes rely on tackling worsening economic hardship.

"Raisi's main challenge will be the economy. Eruption of protests will be inevitable if he fails to heal the nation's economic pain," said a government official.

Khamenei on Wednesday appealed for a large turnout, saying such a show of strength would reduce foreign pressure on the Islamic Republic.

Official opinion polls suggest turnout could be as low as 41pc, significantly lower than in past elections.