Millions of Iranians voted to choose a new president on Friday, urged by Supreme Leader Ayatollah Ali Khamenei to turn out in force to discredit suggestions by arch foe the United States that the election would be a sham.
The 50 million eligible voters had a choice between six candidates to replace incumbent Mahmoud Ahmadinejad, but none is seen as challenging the Islamic Republic's 34-year-old system of clerical rule.
The first presidential poll since a disputed 2009 contest led to months of unrest is unlikely to change rocky ties between the West and the OPEC nation of 75 million, but it may bring a softening of the antagonistic style favored by Ahmadinejad.
World powers in talks with Iran over its nuclear program are looking for any signs of a recalibration of its negotiating stance after eight years of intransigence under Ahmadinejad.
Voting in the capital Tehran, Khamenei called on Iranians to vote in large numbers and derided Western misgivings about the credibility of the vote.
"I recently heard that someone at the U.S. National Security Council said 'we do not accept this election in Iran'," he said.
"We don't give a damn," he added.
On May 24, U.S. Secretary of State John Kerry questioned the credibility of the election, criticizing the disqualification of candidates and accusing Tehran of disrupting Internet access.
All the remaining contenders except current chief nuclear negotiator Saeed Jalili have criticized the conduct of diplomacy that has left Iran increasingly isolated and under painful economic sanctions.
After casting his vote, Jalili said: "Everyone should respect the name that comes out of the ballot boxes and the person people choose," according to ISNA news agency.
Hossein, a 27-year-old voter in Tehran who belongs to the Basij hardline volunteer militia, said he would vote for Jalili, 47, Khamenei's national security adviser and a former Revolutionary Guard who lost a leg in the 1980-88 Iran-Iraq war.
"He is the only one I can trust to respect the values of the revolution ... He feels and cares for the needy," Hossein said.
In Dubai, Iranian expatriate Zahra, 20, a first time voter, said she cast her ballot for Khamenei's diplomatic adviser Ali Akbar Velayati because of his expertise on world affairs.
"When he was foreign minister (from 1981 to 1997), Iran's relations with all countries were better," she said.
The Guardian Council, a state body that vets all candidates, barred several hopefuls, notably former president Akbar Hashemi Rafsanjani, one of the Islamic Republic's founding fathers seen as sympathetic to reform, as well as Ahmadinejad's close ally Esfandiar Rahim Mashaie.
This narrowing of the field prompted concerns of a low turnout which the supreme leader sought to counter.
"What is important is that everyone takes part," Khamenei said. "Our dear nation should come (to vote) with excitement and liveliness, and know that the destiny of the country is in their hands and the happiness of the country depends on them."
The Interior Ministry announced that voting, initially due to end at 1330 GMT, would be extended by several hours, Iran's Press TV reported in mid-afternoon. In the past, authorities have cited such extensions as evidence of a high turnout.
Iran's Sunni Muslim Gulf Arab neighbors are wary of Shi'ite Iran's influence in Iraq and its backing for President Bashar al-Assad and his Lebanese allies Hezbollah in the Syrian war. The Sunni Arab kingdoms are backing the rebels in Syria.
Of five conservative candidates professing unwavering obedience to Khamenei, only three are thought to stand any chance of winning the vote, or making it through to a second round run-off in a week's time.
Nuclear negotiator Jalili, who advocates maintaining a robust, ideologically-driven foreign policy, is seen as the main conservative contender.
The other two, Tehran mayor Mohammad Baqer Qalibaf and former foreign minister Velayati, have pledged never to back away from pursuing Iran's nuclear program but have strongly criticized Jalili's inflexible negotiating stance.
They face Rohani, the sole moderate and only cleric in the race. Though very much an establishment figure, suspicious of the West, Rohani is more likely to pursue a conciliatory foreign policy.
The opposition Kaleme website said Rohani's campaign headquarters had sent a letter to the Guardian Council urging it to remove the name of Mohammad Reza Aref - a reformist candidate who dropped out this week in favor of Rohani - from ballot papers. The complaint said voting slips in some polling stations carried Aref's name and this could create confusion.
With no reliable opinion polls in Iran, it is hard to gauge the public mood, let alone the extent to which Khamenei and the Revolutionary Guards exert their influence over the ballot.
Security has been tight and campaigning subdued compared to the euphoric rallies that preceded the 2009 polls when reformist supporters thought they scented the prospect of change in Iran.
Those hopes were dashed when Ahmadinejad was returned to office by results the reformists said were rigged.
Human rights groups have criticized Iran for further arrests and curbs on activists and journalists ahead of Friday's poll and the disqualification of 678 people registered as candidates.
Iranian officials dispute accusations of human rights abuses and call the charges politically motivated. They also say elections in Iran are free, fair and democratic.