The runoff is slated for 24 June, and Ahmadinejad has already appeared at a news conference to urge his supporters to turn out for that vote, the first runoff presidential ballot since the Islamic Revolution in 1979.
"Everyone is victorious in our elections; nobody has been defeated," Ahmadinejad said. "On top of everyone, our nation was victorious."
According to Interior Ministry figures cited by IRNA today, a total of 26.9 million people voted. With 46.8 eligible voters in Iran, that would put turnout at approximately 57 percent.
Critics in Washington and elsewhere have criticized Iran's political process as run by conservative elements who are able to exclude moderates from meaningful posts.
Hashemi-Rafsanjani had been widely expected to make it through to a second round, but Ahmadinejad was regarded as an outsider going into the ballot.
Reform Hopes Dim
The result represents a blow for backers of political reform in the country, many of whom had pinned their hopes on former Education Minister Mustafa Moin. Moin placed fifth, according to the unofficial figures.
Hashemi-Rafsanjani's main challenges were expected to come from Moin and from conservative candidate and former police chief Mohammad Baqer Qalibaf.
Reports that emerged while polling stations were still open yesterday suggested that Hashemi-Rafsanjani might be bound for a runoff against Moin.
The former hard-line head of Iran's State Broadcasting, Ali Larijani, and Iran's reformist Vice President Mohsen Mehralizadeh fared worst among the seven candidates to replace incumbent President Hojatoleslam Mohammad Khatami, according to the Election Headquarters' initial figures. (For vote figures as reported by IRNA on 18 June, click here.)
Pragmatist v. Hard-Liner
Hashemi-Rafsanjani, the president of Iran from 1989 until 1997, is seen as a veteran politician with lots of influence on Iran's political scene.
Ahmadinejad, a former member of Iran's revolutionary Guard, has cracked down on Tehran's cultural scene since becoming mayor in 2003. At one point, he had a controversial plan to bury the bodies of some soldiers killed during the Iran-Iraq War on one of Tehran's squares.
Outgoing President Khatami, who is barred from a third term by the Iranian Constitution, said yesterday in Tehran that the election will strengthen the foundation of an Islamic democracy in Iran.
[For all our coverage of Iran's ninth-ever presidential election, see RFE/RL's dedicated Iran Votes 2005 webpage.]