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Iran's top leader quickly set the tone Tuesday for his long visit among some of the country's most influential clerics — demanding loyalty to the Islamic state and an end to defiance that has blurred once-clear lines of power since last year's disputed elections.

The planned 10 days of speeches and meetings by Supreme Leader Ayatollah Ali Khamenei in the seminary city of Qom underscore the concerns among Iran's theocrats that their control is under threat by dissent from clerics and the rising influence of security forces after the worst unrest since the 1979 Islamic Revolution.

Khamenei, who has the final say on all state matters in Iran, supported President Mahmoud Ahmadinejad after his disputed election victory in June 2009 and dismissed claims of widespread vote fraud. But many senior clerics in Qom didn't side with Ahmadinejad and have increasingly adopted a critical language against the government.

There also could be an element of legacy building at play. Some experts on Iranian affairs believe the 71-year-old Khamenei may be trying to pave the way for his hard-line son, Mojtaba, to one day take over at the pinnacle of Iran's ruling system.

Such a succession would further alienate Iran's moderate voices. The younger Khamenei is considered a guiding force for the vast paramilitary network, known as the Basij, used to crush opposition demonstrations and bully reformist leaders.

"It's no secret that Khamenei's relationships with some senior clerics have been fraught with tensions since the crackdowns," said Shadi Hamid, a regional affairs researcher at the Brookings Doha Center in Qatar. "These are not small things that can be papered over. They are fundamental to the regime's unity."

By personally carrying the message, Khamenei seeks to confront clerics who have questioned the ruling system and hard-line tactics to keep its grip.

But his mission also brings an element of risk.

Failure to silence criticism in Qom would mark another blow to Khamenei's authority even as the supreme leader and his inner circle are facing pressure from Ahmadinejad's ambitions and allies.

Ahmadinejad has tried to expand his influence into key roles, such as foreign policy, which has been the sole domain of the ruling clerics. He also has forged close ties with the ultra-powerful Revolutionary Guard, which has a hand in everything from the country's nuclear program to commercial banking.

"The (Guard) has become a state within a state. Meanwhile, there is a lot of jockeying for power going on," said Hamid. "This is what really alarms the ruling clerics."

Khamenei hammered this point minutes after arriving in Qom, about 80 miles (130 kilometers) south of Tehran.

"Solidarity ... needs to be strengthened further day by day, specifically with the executive branch (Ahmadinejad's government), which has a lot of burdens on its shoulders," Khamenei told a crowd near Qom's holiest shrine. His speech was broadcast live on state television.

Khamenei didn't elaborate on the struggles facing the country. He didn't need to. They come up every day in the Iranian media and websites.

Iran's central bank says the inflation rate is under 10 percent though many experts say it is more than 20 percent for food and other daily staples.

Companies continue to pull out of the Iran market under U.N. and American sanctions meant to punish Iran for its refusal to halt its nuclear fuel production. The U.S. and allies say Tehran is trying to develop atomic weapons, an allegation denied by Tehran.

Iranian authorities say the oil-driven economy can ride out anything the international community can impose, but plans are under way to sharply reduce costly state subsidies on fuel and basic foods.

For Khamenei, the criticism by Qom clerics carry a specific sting. It challenges the very roots of Iran's system of rule by clerics.

Khamenei was the hand-picked successor to the Ayatollah Ruhollah Khomeini, the charismatic father of the Islamic Revolution who died in 1989. Some followers believe that the supreme leader is divinely inspired and answerable only to God.

In recent weeks, authorities have blocked the websites of at least three senior reform-minded clerics to limit their access to the public and supporters.

Grand Ayatollah Nasser Makarem Shirazi, one of the leading religious scholars in Qom, accused Ahmadinejad's government last month of lying about the country's economic situation.

"Statistics about reducing inflation are constantly released but contradict what the people see by their own eyes," Shirazi was quoted by the media as saying. "When state statistics don't correspond with reality, people lose confidence in government."

The Grand Ayatollah Hossein Ali Montazeri, who died last December, spent years under house arrest after falling out with Khomeini. Last year, he decried the "despotic treatment" of protesters at the hand of the Islamic leadership and accused ruling clerics of committing "crimes ... in name of Islam."

Iran's parliament speaker Ali Larijani, who is close to Khamenei, fired back Sunday. "There is no gap between the leader and the senior clerics," he said, according to the semiofficial Mehr news agency.

Khamenei also is using the extended stay in Qom to boost his own theological credentials.

After Khomeini's death, Khamenei was promoted to the senior rank of ayatollah without the rigorous scholarly work typically required. He also has not published his "treatise," or a book of his teachings, as most senior Shiite clerics do.

Some analysts believe Khamenei may also be testing support for his son Mojtaba to eventually take over.

"This would be the opportunity to try to win backing for Mojtaba," said Rasool Nafisi, an Iranian affairs expert at Strayer University in Virginia. "Khamenei has groomed his son. Now he needs to work on the Qom clerics."

Iran's opposition websites said Khamenei's trip to Qom was taking place under extensive security measures together with costly propaganda to draw a large crowd to give the leader a spectacular welcome.