HERZLIYA, Israel – For the president of the Council on Foreign Relations, Richard Haass, the great hope that Iran’s democrats will throw off the arbitrary rule of the mullahs is a “pipe dream.” That’s what he told some of Israel’s most important strategists Monday for the annual policy conference here.

Sadly, Mr. Haass is not alone in this assessment. He is echoing the conventional wisdom in both Jerusalem and Washington among the spies, diplomats, and analysts that cheering on the opponents of the Iranian regime is not a viable option to prevent the Islamic republic from getting nuclear weapons. As former CIA Persian Gulf analyst Kenneth Pollack writes in his new history of American-Iranian relations, the Iranian people “may not like the regime, but they are not ready to take to the streets to depose it.”

There is certainly evidence that the hard-line clerics are cracking down. Pro-American bloggers have been arrested in the last month and forced to recite apologies to the state. Since February, the hard-line Guardian Council has consolidated power after blocking some 2,000 reformist candidates from running as candidates for the Majlis. Newspapers are closing down and human rights activists are told they cannot leave the country.

But the ascendancy of those still loyal to Ayatollah Khomenei’s vision of a Shiite theocracy should not lead the president to conclude the regime is strong, but rather more fragile than ever. By humiliating President Khatemi and his allies, the ruling clerics risk driving those political leaders that sought to change the system from within to seek to topple it from the outside.

It is to be hoped that additional spurned reformers will join a new movement created last month to push for a referendum on Iran’s constitution that would not only limit the powers of the unelected supreme leader, but enshrine an independent judiciary and basic human rights enumerated in the U.N. charter. A less ambitious referendum was supported by the majority of Iran’s Parliament a year ago, only to have the legislation vetoed by the same Guardian Council that stole the February elections.

The referendum movement is still in its embryonic phase, but it is quite different from prior opposition activities in and out of Iran. To start, the organizers of the effort represent a wide range of Iran’s opponents. It includes Islamic student organizations, which for the last five years have grown increasingly hostile to the regime as they have become disillusioned with Mr. Khatami and his failed promises.

The organization also includes former supporters of the Shah, who from the outside could provide this new united front with much-needed funding. Also, the new effort encompasses many of the original heroes of the Islamic revolution, such as Mohsen Sazegara, who was a founder of the Revolutionary Guard. The fact that Mr. Sazegara is openly identified with the push for a referendum is important because it signals to other leaders of the regime that they will have a future after the regime falls. Like any nonviolent movement, the Iranian opposition must convince the military, intelligence services, and political elites that it is safe to join their side.

Besides unprecedented unity, the new movement for now also has a viable strategy. Since 1999, the Iranian opposition has staged many strikes and demonstrations, but these efforts have failed to collapse the regime because there was no real plan on how to take power. For now, the plan is to collect signatures from Iranians in and out of the country supporting the call for a constitutional referendum. If this is done right, it will create momentum for the kind of massive civil disobedience that will hopefully strip Ayatollah Khomenei’s underlings of the will and desire to carry out the orders necessary to put down the uprising. That’s what happened in Serbia, Georgia, and, most recently, in the Ukraine.

At this juncture, it is in America’s interests to aid the new unified opposition in Iran. But the terms of American support must be dictated by the democrats in Iran. America should not get into the position of either choosing leaders of this new movement or forcing this diverse coalition to agree to policy demands that could hurt them at home.

But failing to see these developments as an opportunity to topple a regime that has served as the model and inspiration of Islamic terrorism for a quarter of a century is just foolish.

The experts are correct when they point out that there is no guarantee the opposition will succeed. But neither is their favored tactic: Multilateral negotiations coaxing, bribing, and threatening the Iranians to abandon their nuclear program. The advantage of a regime change policy for America is that if it does succeed the world be rid of the Islamic Republic of Iran, striking an enormous victory for the democracies in the war on terrorism.

If the intricate diplomacy pursued today by the Europeans succeeds, then America will be partners in propping up a regime that has since its inception been intent on its destruction. That’s much worse than a pipe dream; it’s a nightmare.