In a surprise development, it was the sole reformist who received the most votes Friday. Masoud Pezeshkian, a cardiac surgeon, secured almost 10.5 million votes. He will face off against ultraconservative Saeed Jalili, a former chief nuclear negotiator with just under 9.5 million votes.

Of about 60 million eligible voters in Iran, 24 million people cast their ballot Friday, putting turnout at around 40 percent — a historic low. Iran’s parliamentary speaker Mohammad Bagher Ghalibaf came in third place with about 3 million votes.

The runoff will be held next Friday, July 5, when Iranians will choose between Pezeshkian and Jalili. Iran’s influential Guardian Council, an unelected body of jurists and theologians, will review the results before the top two candidates start campaigning again.

It appears that the conservative vote was split, allowing a reformist to receive the largest share of votes. Two other conservative candidates withdrew from the election days before the vote, but Jalili and Ghalibaf resisted calls for one to step aside. It is unclear if Ghalibaf will give Jalili his endorsement.

Many predicted that the vote would go to a runoff. But some analysts said Iran’s supreme leader Ali Khamenei probably wanted to avoid such an eventuality, due to concerns that a second round of voting could inject additional uncertainty into the process.

For Iran’s ruling clerics, a smooth, predictable electoral process with high voter turnout is important for the regime’s stability and legitimacy.

In the days leading up to the election, Khamenei called on Iranians to vote. “The continuity of the Islamic republic depends on people’s turnout and participation,” Khamenei told reporters Friday after he cast his ballot as polls opened across the country.

Instead, there appears to have been low turnout, motivated by a mix of apathy and opposition to Iran’s clerical rulers. Many Iranians said they would not vote because they don’t believe elections have the power to influence policy, while others said they were disillusioned with a government that has failed to improve their daily lives.