Tehran, Iran (AP) - Iranians voted Friday on whether to keep hard-line President Mahmoud Ahmadinejad in power for four more years or replace him with a reformist more open to loosening the country's Islamic restrictions and improving ties with the United States.
The rowdy election campaign, which lasted less than a month, electrified many voters here and reshaped how the world sees Iran's political process. The mass street demonstrations, polished campaign slogans and televised debates more closely resembled Western elections than the scripted campaigns in most other Middle Eastern countries.
Iran's cell phone text messaging system was down on Friday. Many Iranians, especially young voters -- many of whom favor Ahmadinejad's top opponent -- frequently used text messages to spread election information quickly to friends and family.
Mir Hossein Mousavi, who is in a neck-to-neck battle with Ahmadinejad, accused Iran's telecommunications provider, which is owned by the government, of shutting the system and alleged that some of his representatives were barred from entering polling stations to monitor the vote.
"Unfortunately, some of my representatives were blocked from entering polling stations and SMS (text messaging) is also down, which is against the law," Mousavi said after voting, according to his campaign Web site. "We should not be fearful about the free flow of information, and I urge officials to observe the law."
The spokesman for Iran's telecommunication ministry, Davood Zareian, confirmed to The Associated Press that the text message system has been down since late Wednesday. "We are investigating the case," he said without elaborating.
Election fever took hold of Iran, intensifying dramatically over the final week. Wild, late-night street demonstrations felt more like parties, halting traffic and giving Tehran's youth a rare chance to dance in the streets.
Stakes are high in Friday's vote, both domestically and internationally, even though the real power rests with the unelected Supreme Leader Ayatollah Ali Khamenei. He wields control over every major decision, and the president's powers are limited by the ruling clerics.
Voter turnout is expected to be high Friday -- a factor some say could help sway the vote in favor of the pro-reform Mousavi. Election official Ali Akbar Fadai said Iran would witness a record voter turnout, the state news agency IRNA reported.
At several polling stations in Tehran, lines were long by midmorning as at least 100 people stood waiting to cast their ballots, holding their young children in their arms. In the conservative religious city of Qom, hundreds of clerics and women dressed in long black robes waited for their turn to vote at a mosque.
"I am happy that I could vote. I hope to defeat Ahmadinejad today," said Mahnaz Mottaghi, 23, after casting her ballot at a mosque in central Tehran.
Outside the same polling station, 29-year-old Abbas Rezai said he, his wife and his sister-in-law all voted for Ahmadinejad.
"We will have him as a president for another term, for sure," he said.
After casting his vote in the white ballot box, Khamenei urged Iranians to remain calm.
"As far as I see and hear, passion and motivation is very high among people," Khamenei told reporters. "If some intend to create tension, this will harm people," he added.
After voting at a mosque on Friday in eastern Tehran, Ahmadinejad also commented on the high turnout.
"A strong and revolutionary decision by the people will mean a bright and progressive future for the nation," Ahmadinejad was quoted as saying by IRNA. Mousavi voted with his wife at a mosque in Tehran's southern outskirts.
So far, the country's leaders have not rushed to embrace President Barack Obama's offer to open a dialogue after three decades of diplomatic stalemate. But they left open the possibility of talks in the future. Ahmadinejad has proposed a "debate" with Obama while Mousavi has said he would seek better relations with Washington to try to soften Iran's international image.
The ruling clerics have given no signals that they are willing to switch course on Iran's most contentious issue -- its nuclear program. The U.S. and some of its allies fear Tehran is secretly trying to develop nuclear weapons, though Iran denies it.
Ahmadinejad has repeatedly refused to halt uranium enrichment, a technology that can be used to produce fuel for both nuclear power or nuclear weapons. Mousavi has floated the idea of an international consortium overseeing it in Iran. But both leading candidates say it is Iran's right to pursue nuclear technology.
The race remains too close to call, with a runoff a strong possibility. The winner needs to get 50 percent plus one of the vote on Friday; if neither does, a runoff will be held on June 19.
Mousavi's campaign generated intense excitement among youth in Iran, many of whom boycotted the 2005 elections that brought the Ahmadinejad to power. Mousavi's rallies in Tehran drew tens of thousands of cheering supporters, who later spent their nights shouting anti-Ahmadinejad slogans and dancing to Persian pop songs on the streets.
For the first time in Iran, the forces of the Web were fully harnessed in an election showdown. That catapulted Mousavi, a 67-year-old former prime minister from the 1980s, into a political rock star with the potential to pull off an upset victory with his promises of greater freedom and outreach to the U.S.
Mousavi's wife, Zahra Rahnavard, has also been drawing crowds -- and women's rights advocates have applauded her public role during her husband's campaign. She is the first spouse to take a major campaign role and has promised to keep her voice public if Mousavi wins.
The battle for the presidency turned nasty at times -- especially during televised Western-style debates, another first in Iran.
Mousavi hammered Ahmadinejad's handling of the struggling economy. He made fun of the president's bombastic style, including his questions about the Holocaust that brought Iran international condemnation.
But Ahmadinejad pounced back, claiming the economy has fared better since he has been in power and accusing his rivals of corruption. He also alleged that Rahnavard, a former university dean, did not meet the full requirements to earn her Ph.D. In response, she threatened to sue him.
Even if a reformer wins the vote, it is not clear how far he could push change.
Though the presidency oversees some social programs and has a voice in media and political freedoms, the clerics control the powerful Revolutionary Guard, the judiciary and intelligence services and set all important foreign and defense policies.
Two other candidates are in the race: former Revolutionary Guard commander Mohsen Rezaei and former parliament speaker Mahdi Karroubi. In the increasingly tight race, their level of support could play a swing role -- with Rezaei expected to draw conservative voters and Karroubi pulling in moderates.
Associated Press Writer Anna Johnson contributed to this report.