Events in Iran are at a pivotal moment. This is a struggle over the legacy of the 1979 revolution.
The crisis goes deep. Twenty years ago Hashemi Rafsanjani and Ali Khamenei’s conservative alliance wrestled control of power from reformists like Mir Hussein Mousavi.
Now Rafsanjani’s daughter has been arrested and he is in the religious city of Qom – where Khamenei is unpopular – trying to convince the clergy to move against the supreme leader.
What lies behind this? One factor is Khamenei himself. He lacks the popularity and authority of Ayatollah Khomeini, the founder of the republic.
Khamenei has relied on constitutional changes and radical conservative elements inside the regime to maintain his position.
Another shift is the decline of the reformists.
Despite being a formidable force in the 1990s with a reformist president Mohammad Khatami, by 2005 they had lost power to conservatives.
There were reasons for this. Khatami held the movement back at its peak, condemning students in 1999 who had protested against the banning of reformist newspapers.
The demoralised reformist movement boycotted the presidential election in 2005.
Reformists turned out in huge numbers in this month’s presidential election.
The stakes are high for both the leadership and the demonstrators. Mousavi declared on Friday that he is “ready for martyrdom” and has called for a general strike if he is arrested.
Conservative control has created a debate in a movement which is beginning question the very theoretical foundation of the Islamic Republic.
The majority now believe the solution for Iran is for a separation of religion from the state.
This does not, as some suggest, spell the end of political Islam.
The rooftop chants of “Allahu Akbar” [“God is great”] that echo late into the evening and the “green movement” – representing Islam and peace – are a reminder that religion still provides an important ideological framework.
But the call for secularisation of the state by an Islamist reform movement is a turning point and opens up space for more radical forces to emerge.