A few weeks ago, on 9 July, Iranian-Americans gathered in Washington to show their solidarity with students in Iran who have been campaigning for greater freedom.
Some in the US think recent student unrest is a sign the regime is about to collapse
It was the anniversary of demonstrations in Tehran and other Iranian cities four years ago - demonstrations that were harshly suppressed.
These Iranian-Americans want "regime change" in Iran. But who should take the place of the mullahs who have ruled the country since the overthrow of the Shah in the Islamic revolution of 1979?
Some Iranian-Americans favour the restoration of the monarchy, and look to the son of the late Shah, Reza Pahlavi, who lives in exile in Virginia.
A well-known figure in the Iranian-American community is the businessman, academic and political activist, Rob Sobhani.
"I think there's a role for all dissidents, including the son of the Shah - because Iran today is thirsty for leadership, Iran is thirsty for someone with vision," he says.
Waiting in the wings
"I think what's lacking in Iranian politics today is someone with a vision. I think if that individual - a man or a woman - appears on the scene and grabs the attention of the Iranian people, with a vision of what he or she would like the country to move towards, they will certainly be the beneficiary of that goodwill, that thirst for a leader."
Among the Washington think-tanks there are conflicting views about the credibility of the Iranian opposition.
Reza Pahlavi is a favourite with those who want to restore the monarchy
Patrick Clawson, an Iran-watcher at the influential think-tank, the Washington Institute for Near East Policy, says: "In the external opposition, we've got the People's Mujahideen, who are a very loud and noisy group. They have very little support inside Iran, but they are a useful source of intelligence."
"Scattered in with a lot of misinformation they do have some important titbits - and so we should listen to them.
"Then there's the monarchists and Reza Pahlavi, the son of the late Shah, and he seems to have hit his stride (i.e. improved his performance), and to be learning better how to communicate.
"But a large part of that stride is to avoid any direct role in confronting the mullahs and to avoid presenting himself as someone who should run Iran in the future."
Mr Clawson and others believe the US should give material as well as moral support to the forces inside Iran campaigning for democratic change, including the students and others who have grown disillusioned with the efforts of Iranian reformists, led by President Khatami, to change the country from within.
Some of the right-wing Republicans in Washington, known as the neo-conservatives, think the recent student unrest is a sign that the regime is close to collapse.
John Calabrese of the Middle East Institute, a Washington research centre, takes a different view.
"I think the street demonstrations and protests that have been occurring over the last month or two provide yet additional evidence that there is a deep resentment, a deep alienation - a gulf really - between the regime and the population," he says.
"Having said that, it's also clear from the protests and demonstrations that the regime is resilient, resourceful, and prepared to use repression in order to make sure that the protests are kept more or less under control."
Mr Calabrese believes the weakness of the student demonstrators is their lack of leadership and organisation. He believes the prospects for "regime change" from within are low.
So the two main camps in Washington, the neo-cons and their critics, sometimes known as the realists, disagree over whether "regime change" should be the goal of US foreign policy.
Read more from Roger Hardy in this series on Iran and the US: