Iranians packed polling stations Friday in a tight presidential race between a moderate cleric who became the default choice for reformists and a hard-liner seeking to reclaim the values of the 1979 Islamic Revolution.

The country's first presidential runoff vote capped weeks of campaigning that came down to a choice between sharply differing visions for the future of Iran and its relations with the West.

The narrow winner of last week's first round, Ayatollah Hashemi Rafsanjani (search), has received a flood of support from progressive and business groups seeking to protect reforms made since the late 1990s.

His opponent, Tehran's ultraconservative mayor, Mahoud Ahmadinejad (search), has built on his strong appeal among Iran's impoverished classes and powerful forces opposing any changes to the Islamic regime.

"This is the beginning of a new movement," Ahmadinejad said after voting.

Turnout was strong and voting was extended by four hours until the polls closed at 11 p.m. Lines were long in working-class areas of south Tehran (search), an Ahmadinejad stronghold, as well as in affluent areas of the city where Rafsanjani is favored.

About 63 percent of Iran's nearly 47 million eligible voters cast ballots in the first round June 17.

The earlier vote was marred by accusations of voter intimidation and other abuses, and election overseers warned the Revolutionary Guards and its vigilante wings — both Ahmadinejad followers — to stay clear of polling sites Friday.

Rafsanjani's backers hope the 70-year-old former president will preserve social freedoms and keep a steady hand on Iran's nuclear program (search). Ahmadinejad, 49, sought support among those embittered by the social changes and those who have suffered from the faltering economy.

A 17-year-old voter, Masoud Memarian, said he backed Ahmadinejad "for the sake of God."

Daryoush Hamadi, a 30-year-old Rafsanjani supporter, said, "The country is doomed if hard-liners take the presidency."

Many reformists threw their support behind Rafsanjani, after their main hopeful finished back in the pack during the first round. Rafsanjani got 21 percent of the June 17 vote — well short of predictions, followed by Ahmadinejad with about 19.5 percent. The runoff was forced because no candidate received more than 50 percent of the vote.

"Religious democracy can save the country," said Ayatollah Ahmad Jannati, considered a leading Ahmadinejad supporter.

"Every vote you cast is a bullet in the hearts" of the United States, he told worshippers during Friday prayers at Tehran University.

Political factions and other groups flocked to Rafsanjani's side for the runoff in fear that an Ahmadinejad victory would push Iran back toward the rigid Islamic system of the 1979 revolution.

Rafsanjani, a self-proclaimed moderate, represents the status quo. Backers are confident he will maintain the Western-friendly reforms of outgoing President Mohammad Khatami (search), including business and cultural openings and youth-supported freedoms like dating, music and colorful head scarves for women.

Rafsanjani was Khatami's predecessor, serving as president in 1989-97. He then became a key adviser to the ruling theocracy, which holds near-absolute power over any elected official, including the president.

He also is the head of a family conglomerate that has an airline, the contract to expand Tehran's subway and the bulk of the nation's $400 million pistachio export business.

The cleric is seen as one of the few leaders with the background and authority to challenge Supreme Leader Ayatollah Ali Khamenei and his hand-picked inner circle. Rafsanjani also portrays himself as the best hand to guide the sensitive nuclear talks with the West.

Washington claims Iran's nuclear power program is a cover for building atomic bombs. Iran denies this.

"Rafsanjani can manage the important issues of Iran, especially the nuclear story, in a moderate way," said bookstore owner Reza Khatibi, 47. "If he's not elected, I will leave this country. It will be so dangerous."

A Foreign Ministry spokesman, meanwhile, said Iran will eventually resume uranium enrichment activities no matter who wins the vote, underscoring the limitations faced by the president, whose decisions can be overruled by the theocracy led by Khamenei.

"Whoever is the next president, a permanent suspension is not on the cards," Hamid Reza Asefi said Friday.

Tehran suspended its enrichment program in November as part of negotiations on its nuclear program but has insisted on its right to resume the activities. Uranium enriched to low levels has energy uses, while highly enriched uranium can be used in bombs.

Ahmadinejad, a former Revolutionary Guards commander, draws indirect strength from Rafsanjani's power. In a campaign video broadcast Wednesday, he contrasted his humble populist style with shots of the villa of a previous mayor.

"What we need is justice," he said. "We ask officials: 'Why are you living in palaces?"'

It was a message that resonated strongly in a nation of vast stretches of poverty, despite its oil and gas riches. Ahmadinejad urged a return to the values of sacrifice and common purpose that were espoused after the revolution toppled the U.S.-backed monarchy and the 1980-88 war with Iraq.