Iran’s top leader quickly set the tone 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.

Supreme Leader Ayatollah Ali Khamenei began his 10 days of speeches and meetings in the seminary city of Qom tuesday.

The trip underscores 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 programme 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.”