Tehran, Iran ? A few days in Tehran are enough to dispel the biggest myth about Iran in the Bush administration.

Bush hawks believe Iran is the next stop on the “axis of evil,” but that America doesn’t have to invade the country. Iran, they say, is ripe for implosion.

Its younger generation, which propelled a landslide win by Islamic reformers in national elections, will soon force hard-line ayatollahs out and usher in a secular democracy. The Iraq war will be the trigger that sends this youth wave into the streets.

The image is mesmerizing. Just one problem: An Iraq war is as likely to hurt Iran’s reformers as help.

Iran is indeed going through one of the world’s most interesting internal political struggles. Its people may yet turn the world’s only Islamist theocracy into a democracy with Muslim values, or a system that separates mosque and state.

But not just yet.

Just as Ayatollah Khomeini’s revolution inspired the spread of radical Islam, tomorrow’s Iran someday may become the model for Muslims who want more open systems. Now, however, Iran’s reform process is at an impasse. Islamic conservatives are resisting fiercely, and the once vibrant student movement has faded.

Last week marked the 24th anniversary of Ayatollah Khomeini’s return to Tehran — but the celebrations were listless. At Mehrebad Airport, employees assembled in the ayatollah’s honor in an airless auditorium — women in black chadors on one side and men on the other — to watch a juggler toss large balls to a background of loud ersatz rock music. The juggler kept dropping the balls.

Iranians are fed up with declining per capita income, mounting social problems, and international isolation. In 1997, dissatisfied voters swept a reformist cleric, Mohammed Khatemi, into power. Once forbidden topics — like ending clerical rule — are now debated in the media and on the Internet, though hard-liners have shut down more than 80 reformist newspapers. Rules on dress have been relaxed: Women can be seen in thigh-length coats over pants, rather than enveloping black cloaks, with hair sticking out from their head scarves.

But the country is stuck because Khomeini’s constitution gives unelected clerics a checkmate over the judiciary, the elected parliament, the military and the media. Whenever a crisis looms, it is defused by backroom deals between conservatives and reformers. Despite threats by Khatemi to resign if the clerics derail two parliamentary bills to limit their powers, everyone assures me he isn’t interested in quitting.

“Five years ago, we thought we could reform our regime so we all supported Khatemi,” says Mohsen Sazgara, a onetime revolutionary who returned to Iran in 1979 on the plane with Khomeini. “But when you look back over the past five years, I have to say the reform movement was defeated. Islamists couldn’t reform themselves.”

It is this feeling of paralysis that overwhelms a visitor to Tehran. No one here seems to want a political crisis. People remember the excesses of revolution and don’t want more bloodshed.

Students, who have played a historic role in Iran’s political changes, came to the streets in force in 1999 and seemed poised to provoke upheaval. But they have been chastened by arrests, beatings and disillusionment with Khatemi. Their demonstrations are much smaller now and take place only on campus. The younger generation lacks the strong leftist or Islamist ideologies that propelled Khomeini’s generation to risk their lives for revolution.

That’s not such a bad thing.

But the lack of a compelling vision or a compelling leader seems to guarantee that Iran’s political evolution will develop more slowly than anticipated. The debate remains vibrantly alive — over whether Islam and democracy can coexist, or how to compel a national referendum on the future of clerical rule. But real change is agonizingly slow.

Which brings us to the political impact of an Iraq war.

Many Iranians think it would be a boon to conservatives, who could use it to squeeze reformers to close ranks or to crack down further on media and students.

Will it provoke domestic political change? Only if a new Iraqi government became a democratic model. Like change in Iran, that is a long-term proposition.

Sazgara rightly warns: “Iran is Iran. Unexpected accidents can happen.” But I think those who expect an implosion in Iran tomorrow ought to pay a visit here.

— Trudy Rubin is a columnist for the Philadelphia Inquirer. Her e-mail address is trubin@phillynews.com.