Iran's supreme leader, Ayatollah Ali Khamenei, travels to his country's clerical nerve centre today to demand loyalty and support - or at least silence - from senior clerics in a high stakes bid to bolster his legitimacy.
It is Ayatollah Khamenei's first official visit to Qom in a decade and his first public appearance in the holy city since the disputed presidential election 17 months ago. His standing in Qom and elsewhere in Iran was badly damaged after he declared Mahmoud Ahmadinejad's victory a "divine" blessing that must not be contested.
But it was challenged, and Ayatollah Khamenei - who is meant to be an impartial arbiter - paid a price for supporting his polarising protege. Chants of "Death to the dictator!" - referring to the ayatollah - were common at opposition rallies in the election's tumultuous aftermath.
If Ayatollah Khamenei fails to get what he wants in Qom, "all those Iranian flags that waved" in Beirut during Mr Ahmadinejad's excursion to Lebanon last week will "be useless confetti", said Enduring America, a website with expert Iran coverage.
Qom, a city of lustrous turquoise-tiled mosques on a salty desert plain 160km south of Tehran, has not been immune to the divisions gripping the country.
Some grand ayatollahs known as marjas, or "sources of emulation" - the highest clerical rank in Shiite Islam - have been outspoken against Mr Ahmadinejad's government.
The Grand Ayatollah Hossein Ali Montazeri, who died last year, proclaimed that "no one in their right mind" could believe the official results of the presidential election and said: "A government not respecting the people's vote has no religious or political legitimacy".
Mostly, however, Iran's cautious and conservative clerical class remained silent, although as Ayatollah Khamenei knows, when they do intervene en masse, they have been a powerful force - as they were during the 1979 Islamic Revolution.
Qom's marjas do not live in ivory towers. Their followers pay them religious taxes and follow their rulings. In turn, marjas are responsive to their followers' concerns.
"Marjas reflect the views of ordinary people. These grand ayatollahs talk about inflation, unemployment and other hardships because these issues affect their followers," said a former Qom seminary student now living in Paris. "Shiite religious leadership, if it's not interfered with, is a really interesting democratic institution."
But many of Qom's clerics fear it is being tampered with and they are concerned that their influence is being eclipsed by the military, in particular Iran's Revolutionary Guards.
Iran experts are watching closely to see which senior-most clerics will welcome Ayatollah Khamenei to Qom, who will snub him and who will sit in on his speeches.
One litmus test will be whether Iran's supreme leader is greeted by the Grand Ayatollah Sahid Khorasani, a leading apolitical traditionalist, Iran watchers say. He is the father-in-law of Sadegh Larijani, who heads Iran's judiciary and who, along with his brother, Ali, Iran's influential parliamentary speaker, is a bitter conservative rival to Mr Ahmadinejad.
Opposition websites have reported that Ayatollah Khamenei's excursion to Qom, on today's birthday of Reza, Shiite Islam's eighth Imam, was repeatedly delayed because of difficulties in mustering a respectable show of support.
Iran's supreme leader, whose power eclipses Mr Ahmadinejad's, is keenly aware that those whose help he will solicit in Qom have theological credentials that easily trump his own.
Few in the holy city take seriously his claim to be a marja. Marjas constitute a small number of top religious figures who provide spiritual and personal guidance to millions of pious Shias.
Ahead of Ayatollah Khamenei's Qom visit, the regime blocked the websites of three outspoken marjas who have been critical of the increasingly authoritarian regime.