As the sun set on the fifth day of turmoil over Iran’s disputed election result, the political conflict looked less like a "Tehran spring” challenge to the Islamic regime than a high-stakes game of chicken among its rival factions.

Supreme Leader Ayatullah Ali Khamenei confronts one hard reality: if you summarily ignore the votes that millions of citizens have cast in good faith, even if those votes are against your favorite, incumbent President Mahmoud Ahmadinejad, you could fatally undermine the popular acceptance of Iran’s system of government.

But opposition candidate Mir-Hossein Mousavi faces an equally acute dilemma. As he urges his supporters onto the streets to clash with authorities increasingly prone to use violence, he risks bringing down the very system in which he holds a great stake; on the other hand, holding them back risks simply conceding defeat to Ahmadinejad, even if the verdict of the electorate said otherwise.

Tuesday began with the announcement that the Guardian Council, the 12-member conservative clerical body that oversees Iran’s elections, had agreed to a partial recount of the votes, following opposition complaints — but would not immediately order a new poll, as opposition candidates have demanded.

The council has not ruled out a do-over of the vote, but it won’t deliver its verdict until late next week.

Mousavi had lowered expectations of fairness from the council, reminding supporters on Monday that "many of its members during the election were not impartial and supported the government candidate.” Still, he wasn’t rushing to seek recourse in the parliament of the streets.

Mousavi called off the opposition rally his supporters had planned for 5 p.m. Tuesday in Tehran’s Vali Asr Square, after Ahmadinejad’s government called its supporters to rally against "looters and arsonists” at the same location for a 4 p.m. rally.

Mousavi urged his supporters to stay away "to protect their lives.” (At least seven people are reported to have been killed following Monday’s mass demonstration in support of Mousavi when pro-government militia fired on the crowd.)

The Ahmadinejad rally, which drew a substantial crowd, was a reminder that despite the allegations of massive electoral fraud, the President retains solid support among sizable sections of the population.

And given his strong backing among the security forces and the Basij neighborhood militia, he’s ready to rumble. Mousavi wants to keep his supporters away from violent clashes — which could quickly demoralize them — but as long as the authorities and Ahmadinejad’s allies are willing to spill blood to settle the contest on the streets, Mousavi’s options are narrowed.

Despite their candidate’s calls to stay home, Mousavi backers did in fact rally in the streets of north Tehran on Tuesday, with many thousands marching in silence to demonstrate their anger at the authorities.

A young demonstrator who spoke to the Los Angeles Times at the north Tehran march underscored the complexity of the political conflict under way right now. "We have no leader,” she said.

"Mousavi is a temporary leader, but we need someone to rally around Mousavi is an unlikely leader of a mass "people-power” movement against the government.

A competent technocrat known for his managerial skills, the soft-spoken conservative is very much a creature of the Islamic revolution, having run the government in some of its most difficult years in the 1980s.

He is not even part of the reformist movement led by former President Mohammed Khatami. Mousavi is a leader of the pragmatic conservative wing of the regime, which has been alarmed by the antics of President Ahmadinejad at home and abroad.

He and his allies share the reformists’ goal of getting rid of a President they believe has damaged the Islamic Republic, and the reformists backed Mousavi rather than put up a candidate of their own, believing he had a better chance of beating Ahmadinejad.

No one knows this better than the Supreme Leader himself. As reported by state media on Tuesday, Khamenei met with Mousavi before Monday’s massive opposition protest rally and blamed enemies of the Islamic revolution for the rioting over the weekend.

"You are a different kind from these people,” the Supreme Leader is reported to have told Mousavi, "and it is necessary to follow up things with composure and calm.” In other words, You’re one of us; let’s keep it in the family.

It’s no surprise that Khamenei would try to divide the opposition, achieving some sort of accord with those closest to the conservative establishment, while isolating the reform movement and its most enthusiastic supporters on the streets.

Of course, the Supreme Leader may be hampered by the swagger and militancy of Ahmadinejad and his own supporters on the streets and in the regime, who appear to be in no mood to compromise.

It’s not yet clear whether Mousavi plans to maintain the momentum of his backers on the streets or fight his campaign primarily behind closed doors within the various councils of the regime.

"He’s got some very tough decisions to make,” says Gary Sick, a Columbia University Iran scholar and former National Security Council official.

"If he keeps his people on the streets confronting the authorities, he’s playing with fire. Mousavi, like [fellow presidential candidate Mehdi] Kharroubi and Khatami, may be opposed to Ahmadinejad, but they’re very much part of the Islamic revolution themselves. They were instrumental in creating it, and they’ve been huge beneficiaries of the system. If they push things to the point that risks bringing down the whole system, that would sweep them away as well.”

The same, of course, is true for Khamenei and Ahmadinajad — they, too, are playing a game of brinkmanship that puts the whole edifice of the Islamic Republic at risk.

People voted believing that their votes count; if the outcome shows otherwise, the whole system loses its prime source of legitimacy.

Ahmadinejad doesn’t have things all his own way within the corridors of power, of course. Mousavi has the backing of some very powerful players within the regime, foremost among them former President Hashemi Rafsanjani — a pragmatic conservative who chairs some key councils of the regime, most important among them the Assembly of Experts, which chooses and can even dismiss the Supreme Leader.

Some reports have suggested that Rafsanjani is currently in Qom, the seminarian city where much of Iran’s senior clergy resides, assessing whether he can muster the votes for a challenge to Khamenei by the Assembly of Experts.

That would prompt an unprecedented constitutional crisis in Iran and possibly risk the wrath of the powerful Revolutionary Guard, a key Ahmadinejad power base.

It may nonetheless be dangled as a warning to Khamenei in the behind-closed-doors bargaining that may ensue. The apparent swings in the positions adopted by key regime figures like parliament speaker Ali Larijani, who has alternated between urging the country to unite behind Ahmadinejad and loudly condemning attacks by security forces on opposition supporters, suggests a fierce battle may be under way for backing within the regime.

Also weighing on Mousavi will be the fate of former President Khatami, who faced a similar challenge in 1999 when a mass movement took to the streets to support his reformist agenda when conservatives in the regime used their power to block his initiatives.

Pro-reform demonstrators were savagely and systematically attacked by the security forces, and when they turned to Khatami for leadership, he essentially told them to go home. Says Sick: "That was the point at which people lost confidence in the reformist movement.”

TIME