His closest opponent is conservative cleric Ebrahim Raisi, who has cast doubt on the benefits of the nuclear deal.
Iran’s Supreme Leader Grand Ayatollah Ali Khamenei was among the first to cast his ballot and urged others to do the same. “I believe that the presidential election is very important. The fate of the country is in the hands of people,” he said.
Raisi is widely seen as Khamenei’s preferred candidate — indeed, he is often mentioned as his possible successor.
For many in Iran, especially in affluent areas of the capital, Tehran, Rouhani has provided a glimpse of what many have long desired — engagement with the outside world, without the types of banking and visa restrictions, as well as economic sanctions — that left them feeling so isolated.
Reform-minded supporters recognize that Rouhani isn’t perfect — he too, after all, is also a cleric. But he’s widely seen by reformers as their best hope for change.
A CNN crew in North Tehran, where there are a lot of moderate Rouhani supporters, saw long lines at one polling station, with some people waiting more than two hours to vote despite the scorching heat.
Voter Mahya Kamalvan, 26, told CNN: “We cannot complain if someone else is chosen. We have to prove that we are here, we support what we want. And then if anything happens the other way, maybe we can say something.”
Another voter, 22-year-old medical student Yasaman Allahgholy, said it was her duty to vote to “make my country more free, and be more popular in the world,” and that it was important to protect the real improvements she has seen recently in Iran’s medical system.
“I am young, and I want to live in a more free country. To show what I think without fearing from being in jail or something like that,” she said.
“When we fight with other countries, when we show an angry face to other countries, our economy will decrease little by little. So it’s really important for me to participate in this election, for my future.”
“It’s the reason why I have [waited] about one hour in this line, in this hot weather.”
Should Raisi win, Iran is expected to retreat from the kind of nascent international engagement seen during Rouhani’s first term.
Raisi’s history may deter some voters — the 56-year-old cleric was a member of the so-called “Death Commission,” which presided over the summary executions of thousands of political prisoners in the summer of 1988.
But Rouhani won’t necessarily benefit.
Ahmad Majidyar, who leads the IranObserved Project at the Middle East Institute, believes that “many reformists are dismayed by the President’s unwillingness to stand up to the country’s judiciary and security establishment,” meaning many may simply not bother to vote at all.
In a tight contest, a traditionally high turnout among conservatives could be enough to give Raisi victory.
However, Rouhani has history on his side: no sitting President has failed to win a second term since 1981.
Official results, announced by Iran’s Ministry of Interior, are not expected until later this weekend. If no one candidate achieves an absolute majority — over 50% of the vote — a runoff will take place on May 26.
The president has had a tough time defending the 2015 nuclear deal and his opponents have accused him of not making good on his promises. Debates have largely centered on this issue.
Rouhani billed the deal as one that would thrust open the gates of economic opportunity, bring the country out of its isolation and create millions of jobs for Iranians.