TEHRAN , Iran -LRB- CNN -RRB- -- Defying many predictions , Iranian President Mahmoud Ahmadinejad held a commanding lead in the presidential vote count early Saturday , election officials with Iran 's Interior Ministry said . Men choose their candidates before voting Friday at a mosque in Tehran , Iran . With 72 percent of ballot boxes counted , Ahmedinejad had 65.7 percent of the vote while his chief rival Mir Hossein Moussavi had 31.4 percent , election officials said . Moussavi , widely regarded as a reformist , had been expected to do well as his campaign caught fire in recent days , triggering massive street rallies in Tehran . An `` unprecedented '' voter turnout at the polls Friday was also expected to boost Moussavi 's chances of winning the presidency . Iran 's Interior Minister Seyed Sadeq Mahsouli said 70 percent of 46 million eligible voters had gone to the polls Friday , according to Fars , another semi-official news agency . Both candidates claimed victory . Moussavi 's camp accused the Iranian establishment of manipulating the vote . Watch why each side is claiming victory '' Voting was supposed to end after 10 hours , but because of the massive turnout , officials initially said polling stations would remain open until everyone in line had a chance to vote . However , Moussavi alleged that doors were being closed with people still waiting outside . Some private news agencies reported many Iranians were milling about on the streets late into the night . Mehr reported that the chief of police declared public gatherings of candidate supporters illegal . Earlier in the day , voters crowded the steps of one polling place in Tehran , some waiting more than three hours underneath the hot sun to cast their ballots . Some were lining up even before the polls opened at 8 a.m. Moussavi is the main challenger among three candidates vying to replace Ahmadinejad . The other candidates are former parliament speaker and reformist Mehdi Karrubi , and Mohsen Rezaie , the former head of Iran 's Revolutionary Guards . Mehr reported Rezaie had 1.72 percent of the vote and Karrubi had 0.87 percent . If no single candidate reaches a simple majority -- 50 percent plus one vote -- a runoff election will be held on Friday , June 19 . It was unclear where the ballots that had been counted so far had been cast . Ahmadinejad still has staunch support in Iran 's rural areas , but has been blamed for much of Iran 's economic turmoil over the last four years . If he loses , it would be the first time a sitting Iranian president has not won re-election to a second term in office . Fawaz Gerges , an academic and author who studies the region , said Friday 's vote is really `` a referendum on Ahmadinejad , '' who has been in office since 2005 . `` The unemployment rate is 30 percent ... the largest in the third world , inflation is -LSB- in the -RSB- double digits in Iran , '' Gerges told CNN 's `` American Morning . '' `` We focus in the United States a great deal on his inflammatory rhetoric on the Holocaust , on nuclear weapons . We tend to forget that Ahmadinejad has basically done a great deal of damage to the Iranian economy , on social policy . '' While Moussavi 's campaign has energized key segments of Iranian voters -- particularly women -- Gerges noted that `` Iranians have surprised us many times . '' Moussavi 's supporters crowded the streets of Tehran this week , wearing the candidate 's trademark color green . His campaign has also energized Iran 's youth , many of whom did not take part in the 2005 election . Yasmin , a 21-year-old university student , said she cast her ballot on Friday for Moussavi . CNN 's Christiane Amanpour reports emotions on the street '' `` I 've never even been interested in the politics of my country until today . It was my first time voting , and I am so excited about it , '' she said . `` We are all yearning for change , and I believe Moussavi will bring much more freedom to Iran and our lives . That is why I cast my ballot for him . There is so much anticipation in the air . '' Moussavi 's supporters hope that he follows in the same footsteps as Mohammed Khatami , a reformist candidate who overwhelmingly won the presidency in 1997 , raising hopes that the reformist movement would bring religious and democratic freedoms to the Islamic republic . But the real power in Iran rests in the hands of Supreme Leader Ayatollah Ali Khamenei . By the time Khatami left office in 2005 , he was unable to make major changes because of the opposition of hard-line elements in Iran 's clerical establishment . `` The elected president is not the commander in chief , he does not make decisions of war and peace , '' Gerges noted . `` The major decision maker -LSB- in Iran -RSB- is the unelected supreme leader , that is Ali Khamenei , along with a National Security Council . '' But Gerges noted that the `` the style of the president '' and his `` posture '' have a great deal of influence on Iran 's relations with other countries , particularly the United States . Watch CNN review the unprecedented online presence of candidates '' No matter who wins Friday 's vote , analysts say it is unlikely any of the candidates would change Iran 's position on its nuclear program , which the Islamic republic insists is for civilian purposes but the United States and other Western powers believe may be a cover for a weapons program . Iranian-American analyst and scholar Reza Aslan said that while Moussavi is `` a little bit more of a moderate when it comes to the nuclear issue ... all four candidates agreement with Iran 's right to develop nuclear . '' Nevertheless , Aslan said that all four candidates also `` recognize it 's time to open up to America and to the international community because there 's no other option with regard to the economy . '' CNN 's Christiane Amanpour , Samson Desta and Mitra Mobasherat contributed to this report .