Keeping options open: Reza Pahlavi
Reza Pahlavi is the eldest son of the former Shah of Iran, Mohammad Reza Pahlavi. Followers see him as the heir to the Peacock Throne.
Since the death of his father in exile in 1980, he has been a focus for monarchists and other dissidents hoping to oust the authorities in Tehran.
Some Washington hawks are said to regard him as their most promising ally in pushing for regime change in Iran.
In 1979, when his father was swept from power, Reza Pahlavi was in Texas completing his air force training.
After a number of years in Egypt and Morocco, he moved to a Washington suburb in 1984, where he still lives with his wife and two daughters.
The extent of his support among Iranians at home and abroad is difficult to gauge.
But since the reformists' poor showing in local Iranian elections in early 2003, there are signs Reza Pahlavi is seeking to broaden his constituency in a possible bid for a future political role.
"In the past I defended the idea of a constitutional monarchy," he told a Turkish newspaper in June 2003. "But my views have changed. I think the best for Iran is a secular and democratic system."
His vision for Iran is set out on his website. It speaks of a country in the "abyss" of isolation, inflation, unemployment and corruption.
The time has come to write a "new chapter", it says, where freedom and prosperity for Iranians, including women, are guaranteed. The way ahead leads through a referendum, then on to "free and fair" elections.
In June 2003 he told London's Financial Times that regime change could happen "in months, or in one or two years".
Comparing the situation in Iran to the economic decline of 1978, which precipitated the Islamic Revolution, he said he was committed to "non-violent civil disobedience".
And he appealed to the opposition to organise an Afghan-style loya jirga to map out the future.
But, according to Iranian media, Reza Pahlavi's campaigning has not gone down well at home.
Reformists have criticised what they see as his attempt to exploit the June student unrest in Tehran to further his own political ends.
BBC Monitoring, based in Caversham in southern England, selects and translates information from radio, television, press, news agencies and the Internet from 150 countries in more than 70 languages.