Amid scattered deaths and rising protests, the showdown in Iran continues to build. The Iranian regime’s crackdown is gathering momentum, with reports of sweeping arrests of opposition figures, militia raids on university campuses, and threats from the Iranian Revolutionary Guard Corps that protestors are liable to be executed. (A contingent of pro-Ahmadinejad backers marched in Tehran yesterday, chanting: “Rioters should be executed!”) According to Reuters, the Guard statement said:

“We warn the few elements controlled by foreigners who try to disrupt domestic security by inciting individuals to destroy and to commit arson that the Islamic penal code for such individuals waging war against God is execution.”

Of course, the “elements” are hardly “few,” they are not “controlled by foreigners,” and their actions have been overwhelmingly nonviolent, dignified, and restrained rather than trying to “destroy” and “commit arson.” Yet the threat is plain.

Ibrahim Yazdi, the dissident veteran of the 1979 revolution who is a leader of the Freedom Movement of Iran — and who I interviewed at length at his home in Tehran the day after the rigged election — is reportedly sought by the Iranian security forces, who came to home to arrest him. He was not there, according to the report. The Washington Post reports that more than 170 opposition figures have been arrested, including senior officials.

The anti-Ahmadinejad coalition is deep and broad. It includes conservative, Old Guard founders of the Islamic Republic, who view Ahmadinejad with disdain and who resent the coming to power of his coterie of Revolutionary Guard commanders; the large and growing majority of Iranian clerics and senior ayatollahs, many of whom have long viewed the Leader, Ayatatollah Ali Khamenei, as an upstart and usurper since he was elevated to his position 20 years ago; nearly the entirety of Iran’s business class, especially those involved in high-tech, aviation, oil and gas, and heavy industry, who blame Ahmadinejad for his catastrophic mismanagement of the economy and for the crippling economic sanctions; the entire class of Iranian reformists, from more liberal-minded clerics like former President Khatami to more centrist ex-officials such as former Prime Minister Mousavi, the presidential candidate; a large contingent of Iranian women, energized by the role of Zahra Rahnavard, Mousavi’s wife, who I met in Tehran, who campaigned vigorously for her husband and for women’s rights; and of course, the educated elite of Iran, including students, artists, filmmakers, intellectuals, writers, and musicians.

The pro-Ahmadinejad bloc is a typically fascist one. It includes, first of all, the 150,000-strong Revolutionary Guard, the paramilitary, million-strong Basij militia, thug-like, unofficial vigilante groups like Iranian Hezbollah (unrelated to Lebanon’s Hezbollah), the police, and other security forces. Important elements of the national security bureaucracy, who are on Ahmadinejad’s payroll, support him enthusiastically. An increasingly isolated, and very hard line, bloc of senior clerics — including Khamenei, members of the all-powerful Guardian Council, and an ultra-conservative group of clerics in Qom, centered on followers of Ayatollah Mesbah-Yazdi and his students — supports Ahmadinejad, though they are arrayed against the opposition clerics. And of course, Ahmadinejad has a loyal base among the religious right, rural and small town voters who’ve been showered with petty largesse under his rule, and ultra-nationalists who find his appeal to defiant anti-Westernism stirring. The Revolutionary Guard, which has constructed a vast economic enterprise in Iran, is skimming profits, smuggling banned goods, and elbowing out Iran’s battered private sector.

My own view — and this was confirmed by a number of insiders I met with in Tehran — is that the traditional balance of power has been upended. According to conventional wisdom, Iran’s president is a figurehead with little or no power, while the Leader (often mistakenly called the “Supreme Leader”) is the all-powerful commander in chief and decision-maker. At the very least, that balance is tilting, and I’ll leave it to closer watchers of Iranian politics than me to figure out how far it’s moved. But it’s clear that Ahmadinejad, his military and paramilitary allies, and the radical clerics that support him have at least surrounded if not neutralized Khamenei, the Leader.

Part of the stuggle that’s unfolding now is a struggle for the Leader’s allegiance. Key allies of Mousavi, above all Ali Akbar Hashemi-Rafsanjani, the corrupt billionaire and fixer who helped Khamenei come to power in the late 1980s, have been outraged by Ahmadinejad’s bungling and mismanagement. If — and this is a big, big if — if the entire pro-Mousavi coalition I described above were to continue to challenge Ahmadinejad’s rigged vote, if the street protests continue unabated, and if enough of Khamenei’s former allies (like Rafsanjani, who met with Khamenei the day before Friday’s election) can pull enough strings, it’s possible that Ahmadinejad could be ousted in what would amount to a palace coup. That’s very unlikely, but possible. And it is far from clear that Ahmadinejad would go quietly, even in that case.

The first inkling that the election outcome could be reversed was the statement from the spokesman for the Guardian Council, Abbas Ali Kadkhodai, that the current review of the vote by the Council, ordered by Khamenei and expected to take a week to ten days, might “result in the nullification of the results and the holding of a new election,” as the Washington Post reported. “That is not implausible,” Kadkhodai said, to Mehr News, an Iranian press agency with government ties. One analyst has speculated that such a scenario could involve the Council disqualifying enough of Ahmadinejad’s votes to bring his total under 50 percent of the vote, thus forcing a runoff election between Ahmadinejad and Mousavi. To be sure, such an event would be nearly revolutionary, and it would further embarrass the Leader, who called the election results last Friday “sacred” and “blessed.”

More likely is that Khamenei, Ahmadinejad, and their allies will circle the wagons. They’ll greet protests with an iron fist. Though things are ugly now, they could rapidly get a lot uglier, more violent, and more civil war-like. Thirty years ago, it was the decision of the Shah of Iran not to confront the revolutionaries with violence that allowed the anti-Shah movement to grow strong enough to oust the Shah. Then, as now, a relatively small number of deaths — “martyrs” — triggered a traditional, Shiite forty-day cycle of memorial marches and ceremonial protests and led to a crescendo of protest by the end of 1978. A month later, the Shah had fled.

So far it’s unclear if the opposition can maintain its momentum. I’d say that the smart money is on Ahmadinejad holding on, backed by outright force. That’s why President Obama is hedging his bets, praising the rebellious students and Mousavi voters but insisting that he’s ready, willing and able to talk to Ahmadinejad and Khamenei. To the continuing frustration of the neocons, Obama isn’t throwing American support to the Green Revolution. And that’s a good thing.

As for me, well, I’m biased. I support the Green Revolution. But I’m not being shot at.

That doesn’t mean that I support Iran’s reactionary, benighted form of government. As far as I am concerned, a government run by mullahs is so seventh century. Do Iranians want to upend the entire system? Many do. Many Iranians are sick and tired of, and embarrassed by, a regime run by bearded old clerics. How much of Mousavi’s coalition is made up of people who want to do away with the entire Iranian constitution and the Islamic Republic that goes with it? My guess? Except for Rafsanjani, his clerical allies, and others in the establishment, quite a few. Many of those who were attracted to Mousavi and Rahnavard supported them because they saw the reformists as a key that might open a locked door to a new Iran, one run by secular politicians. “Tis a consummation devoutly to be wished,” said Hamlet. Of course, the princely Dane was talking about suicide. And for many Iranians, opposing the Iranian regime means exactly that.