Everyone is asking the same question: What comes next?

TEHRAN, Iran—Everyone on the streets of the city is wondering the same thing: "What will happen today?" They ask one another and turn to foreign journalists as if we have an answer. We don't.

While no election result is ever clear until every ballot has been counted, the path to victory in the Iranian presidential vote is especially murky.

The last eight days have seen unprecedented displays of public expression and exuberance for the Islamic republic, and no one can make sense of what it means. Many think it is a temporary manifestation of youthful frustration, little more than a passing fad. Others take it as the last breaths of a decaying theocracy. Personally, I don't believe either theory.

The lack of reliable polls or survey statistics—and Iranians' propensity for spreading imaginative rumors—makes the fight, thought by most to be between incumbent Mahmoud Ahmadinejad and reformist former Prime Minister Mir Hossein Mousavi, even more opaque. In 2005, just days before voting, Ahmadinejad wasn't even polling in the top four. Iranian public sentiment is about as predictable as a game of craps.

The street rallies have been overwhelmingly peaceful, largely because Ahmadinejad and Supreme Leader Ayatollah Ali Khamenei have asked the Basij, the regime-funded armed militia, to behave. So far they've complied. We'll see how long that lasts. It seems likely they will be out in full force tonight, patrolling the streets to ensure that the spontaneous crowds seen during the campaign don't reappear.

Mousavi's supporters are much less organized than the Ahmadinejad camp. At times it seemed that they were acting the way they thought freedom should look: dancing in the streets, blaring their music, and painting their faces green, the Mousavi camp's signature color. It felt more like Mardi Gras—without the booze—than a political campaign. The mudslinging, harsh accusations, and the local TV stations' blatant bias toward Ahmadinejad only seem to add to the carnival-like atmosphere.

For the first time in eight days, the streets of Tehran were quiet last night, due to an official 24-hour quiet period before voting began. Many are exhausted from the succession of late nights, and everyone is anxious.

Rather than predict who will be Iran's next president, let me propose two scenarios, both rather gloomy:

Should Mousavi win, and especially if he secures victory in the first round of voting, I fear violence may take over the streets of Tehran, at least for a time. The Basij have remained calm thus far, but no one expects that to last forever. They've mirrored their candidate's demeanor in recent weeks, and although Ahmadinejad plays "man of the people" adeptly, there is no way he will go quietly. Like George W. Bush, he has a strong sense of divine entitlement.

While Mousavi has come to represent the dream of a freer and more open Iran, more and more people seem to be caught up in the belief that anything would be better than four more years under Ahmadinejad.