He's quiet and secluded, but Ayatollah Sistani is likely to play a major role in Iraq's future, writes Paul McGeough from Baghdad.
It is impossible to escape Iraq's past in the gold-domed ci|y of Najaf. But after a few hours in the pilgrim city's tea houses and spiritual backrooms, an outline of this benighted country's future emerges - and it's not what George Bush envisaged.
Najaf is a shrine for Iraq's long oppressed Shiites, who make up 60 per cent of the population.
The tomb of their saint of saints, Imam Ali, is here because the 7th century martyr instructed his army that, should he die, his body was to be strapped to a camel and he was to be buried where the camel rested. Such is the will of Shiites worldwide to be interred near Ali's tomb, that the city boasts the biggest cemetery in the Middle East.
Najaf also remembers its recent dead. Its crumbling walls are papered with the faces of Saddam Hussein's Shiite victims. Post-Saddam, they have been joined by the beatific visage of Ayatollah Mohammed Baqir al-Hakim, a prominent Shiite leader who, with 89 others, died in an August car-bomb attack outside the mosque housing Ali's tomb.
Only eight months since President Bush landed his invasion force in Iraq, Najaf has reasserted itself as the spiritual heart of the country and the back-ally office of the white-bearded Grand Ayatollah Ali al-Sistani is fast becoming a serious rival to Baghdad as a seat of political power.
Ayatollah Sistani, who commands inordinate respect among Shiites, has bided his time, seemingly giving the US coalition the opportunity to make good its liberation promises by urging Shiites not to resort to violence against the Americans.
But the man is an enigma. He has no political party and no army. He rarely speaks his mind and he hardly ever ventures from the home where he receives few guest - and certainly not Mr Bush's man in Iraq, Paul Bremer.
In June he quietly issued a fatwa, insisting on the right of all Iraqis to have a direct say in electing a new government and the experts to draft a new constitution.
The Americans made the mistake of concluding that the frail old man of Najaf could be ignored. Late last month Washington was forced to buckle to Ayatollah Sistani.
It was obliged to dump its plans for political transition in Iraq, abandoning a timetable that it hoped would give more secular and US-friendly political forces time to take control in a fledgling democracy in a community in which one of the few threads to survive Saddam was the mosque, and the only players were powerful dynastic religious families that for years had been at war but which are proving adept at sensing the political mood.
Washington feared that as an unsophisticated electorate trampled for decades by Saddam, Iraqis would be too easily guided by the mullahs. But as the majority that has never ruled in Iraq, the Shiites saw the deferral of direct elections as a US attempt to craft the democracy it wanted, one in which the force of their numbers might be diminished.
Now, the extent to which the US can shape an Iraqi administration has become an open question.
Having delivered the alien concept of democracy to the gates of Baghdad, it has found Ayatollah Sistani to be the most ardent in embracing its fundamentals - which he now uses to push back all US efforts to shape developments to its liking.
As midwife for the model democracy that it says the Middle East needs, it is almost impossible for Washington to dispute the Iranian-born ayatollah's seemingly non-negotiable bottom line that all Iraqis should elect their government and the panel that will draft the constitution.
It has caved in on the constitutional issue and the haggling continues on how to elect Iraq's new government next year.
All the key Shiite leaders are clerics.
After Ayatollah Sistani, the most prominent are Abdel Aziz al-Hakim, a brother of the assassinated Ayatollah Hakim, who stepped into the dead man's shoes as leader of the Supreme Council for Islamic Revolution in Iraq. Sheik Hakim has co-operated with the US, taking a seat on the Washington-appointed Interim Governing Council, while at the same time embracing the Sistani line.
On the fringes is the anti-establishment firebrand, Muqtada al-Sadr. About 30, he tries desperately to fill the shoes of his much respected father - who was killed by Saddam - and though he has been elbowed from the top table, Sheik Sadr has strong support in the teeming slums of Baghdad and in other pockets of the country.
He too embraces the Sistani line, but only to the extent that it fits naturally with his more virulent anti-American rhetoric. This week he told a press conference in Najaf that killing Americans did not constitute terrorism.
The Hakim and Sadr families vie for more than political power. Each has their own army and while much of the roiling between them centers on family prestige and honour, a lot has to do with control of the massive pilgrim donations that a lot has to do with control of the massive pilgrim donations that pour through the mosques of Najaf and nearby Karbala.
Among some Shiites there is a very matter-of-fact debate, which seems to take place with absolutely no sense of outrage, about how long it will be before Sheik Hakim's militia kills Sheik Sadr.
The difficulty in understanding the position of these men - Ayatollah Sistani included - is that they speak in riddles or not at all.
Yet, as the chaos of the US occupation continues to compare badly with the oppressive order of the Saddam years, the clerics are seen to be gaining power.
Under Saddam, Ayatollah Sistani was silent. What is not clear is the extent to which this was about protecting his followers from more regime-inflicted pain as much as it might have been a rejection of the insistence of his Iranian counterparts that the most scholarly clerics should rule or oversee government.
Likewise, it is only apparent that he is intervening directly in the political process now because of the prize of political control that Shiites see within their grasp.
There is much second guessing - as much by the Americans as by Iraqis.
In an interview, Said Kamaleddin al-Muqaddas, one of Ayatollah Sistani's two representatives in Baghdad, dismissed the Sunnis as "only 20 per cent of Iraq".
"If Sistani says anything, all the political parties will respect him," he said.
Swathed in brown robes and sitting on the cushioned floor in his home in inner Baghdad, he said: "The Sunnis have ruled Iraq for too long. The new government will be Shiite."
Then he seemed to lecture Washington on the basics. "It's like Britain and the US - the majority vote wins and if Washington doesn't like that, what can they do?"
Without stating it, he introduced an Iranian analogy into the debate. "Sistani will see the written constitution before he endorses it, but he is big enough and powerful enough to reject it. And whoever is the president of the ICG needs to keep going to Sistani to get his permission for what the council is doing."
He shed only a little light on Ayatollah Sistani's thinking. "I have spoken to him about the government we will have, and he said that the most important thing is not about being 100 per cent like Iran, so much as having safety and security for the people of Iraq."
In Najaf, Aboud Zaid al-Jabbari runs the local branch of the Supreme Council for Islamic Revolution in Iraq. Like the officials of the former regime who wore Saddam watches, the face of his timepiece bore the image of a Shiite holyman.
Mr Jabbari is reluctant to name countries that an Iraq governed by Shiites would emulate.
But asked about the role of Ayatollah Sistani, he said simply: "...we are waiting for who and what he chooses. Yes, he is so supreme that he does not have to be elected and he does have a power of veto. All Iraqi people respect the religious scholars and they say 'yes' to what the scholars decide."
Asked why Ayatollah Sistani was so Delphic in the absence of Saddam, he said: "He is still afraid to use all his power, even though Saddam is gone. But if he doesn't agree with the new constitution, the people of Iraq will never agree to it."
Searching for a western equivalent, he suggested: "Sistani is our version of the Pope... If Sistani calls for the people of Iraq to die, they are ready."
Everything is blurred in Iraq - power, religion and politics. While the Iraqi exiles the Americans airlifted to Baghdad in the first exciting days of liberation and most of the new Iraqi political parties lunged for the institutions of power, the Shiite leadership went to the people and now seem to be better placed politically.
The US confidently believed it was bringing a savvy and suited new elite to Baghdad in the form of the exiles.
It gave them an armchair ride into positions of power, but now Washington is confronted by a robed and bearded near-saint who says very little, but who means what he says.
Even if Ayatollah Sistani compromises to accept an initial framework that allows President Bush to again unfurl the "mission accomplished" banner, there are fears among non-secular Shiites and non-Shiite Iraqis that a Sistani dominated regime might quickly evolve into something very different, perhaps something very theocratic, maybe something very Iranian.
How does the US stop a new Iraqi regime from spiralling into a pale imitation of the charades of democracy in so many Muslim countries?
The difficulty facing Bremer is how far back he can push Ayatollah Sistani, before the ayatollah - or others in the Shiite leadership - urge Shiites to line up with the Sunnis against the US occupation.
As events are unfolding, Ayatollah Sistani is a powerful political force. Yet he exists outside the political process, effectively ruling by fatwa, by talking in riddles or simply remaining silent and allowing others to guess his position.