One of Iran's most powerful men may be playing a key role behind closed doors in the country's escalating postelection crisis.

Former president and influential cleric Ayatollah Hashemi Rafsanjani has made no public comment since Iran erupted into confrontation between backers of hardline President Mahmoud Ahmadinejad and reformists who claim he stole re-election through fraud.

But Iranian TV has shown pictures of Rafsanjani's daughter, Faezeh Hashemi, speaking to hundreds of opposition supporters. And Rafsanjani, who has made no secret of his distaste for Ahmadinejad, was conspicuously absent from an address by the country's supreme leader calling for national unity and siding with the president.

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Supreme Leader Ayatollah Ali Khamenei praised Rafsanjani, 75, on Friday as one of the revolution's architects and an effective political figure for many years, but he acknowledged that the two have "many differences of opinion."

"Of course, the president's ideas are closer to mine," Khamenei said, warning opposition candidate Mir Hossein Mousavi and his supporters to halt protests or face the consequences.

Demonstrators clashed with security forces in Tehran on Saturday despite the ultimatum in the most widespread violence of the crisis. There were unconfirmed reports of violence in other Iranian cities.

While his true views, and even his whereabouts, remain unclear, any support for the opposition would place Rafsanjani in direct conflict with many of the most powerful clerics in Iran's highest echelons of power.

The stakes for the world are high.

Iran is pressing ahead with its nuclear program in the face of international sanctions and Israeli threats of military action. The United States and other Western nations maintain that the program is geared toward making a bomb, a charge Iran consistently denies.

Meanwhile, President Barack Obama is seeking to improve relations with Iran, ending 30 years of animosity that have helped define the Islamic Republic.

The regime's militant wing, with Ahmadinejad its most visible face, takes a hard-line position on relations with Washington and is determined to push forward with the nuclear program regardless of the consequences, experts say.

A camp of pragmatic clerics and politicians led by Rafsanjani, while loyal to the revolution's principles, wants to build better ties with the West and a more friendly image of Iran.

"What is clear is that the leadership is far more polarized and splintered than has been clear in the past," said Anthony Cordesman, a former Pentagon analyst with the Washington-based Center for Strategic and International Studies.

Friday's comments showed the country's ultimate authority is firmly behind Ahmadinejad, who has publicly accused Rafsanjani and members of his family of corruption. Experts said that could mean Rafsanjani's power is waning.

"Now that the leader has made clear he was supportive of Ahmadinejad and sharing the same vision of the future of the Islamic Republic, it can be taken as a major defeat for Rafsanjani and for the political options he promotes," said Frederic Tellier, an Iran expert in the International Crisis Group, a Brussels-based think tank.

Iran's crisis began when Mousavi, a reform-minded architect who served as prime minister in the 1980s, claimed he was the victor of the June 12 election, accusing Ahmadinejad of using widespread fraud to win it.

Mousavi insists he wants a new election, an option Khamenei ruled out.

Rafsanjani was president between 1989 and 1997, but failed to win a third term when in 2005, losing to Ahmadinejad in a runoff. He was a close follower of the late Ayatollah Ruhollah Khomeini, father of Iran's Islamic Revolution. He now heads the Expediency Council, a body that arbitrates disputes between parliament and the unelected Guardian Council, which can block legislation.

He also is the head of the powerful Assembly of Experts, which comprises senior clerics who can elect and dismiss the country's supreme leader.

Alireza Nader, an expert on Iran with the RAND corporation, says Rafsanjani retains some leverage against Khamenei and Ahmadinejad as chairman of the Assembly of Experts. However, he says, Khamenei ignored a letter Rafsanjani wrote asking him to restrain Ahmadinejad, who accused the former president of corruption in a televised debate.

Ignoring the letter, Nader said, "was perceived by many Iranians as a rebuke to Rafsanjani and his role in the political system."

Rafsanjani's influence may have significantly dissipated as a result, he said.

"Rafsanjani is a son of the revolution," said Tellier of the International Crisis Group. "But his own future depends on how far the leader will allow Ahmadinejad to go in his attacks against Rafsanjani and his family."