Tens of thousands of Iraqis have demonstrated in the southern city of Basra in support of a call for early elections from the country's leading Shia cleric.
Shia objections are complicating American plans to hand over power to an appointed Iraqi government by 1 July.
As they begin to realise that self-government may be within their grasp, Iraq's religious and tribal leaders - and its new and old political parties - are jockeying for position.
Many Iraqis took to Basra's streets to back calls for direct elections
The call for early elections from the leading Shia cleric, Ayatollah Sistani, is proving a powerful rallying-cry among his community.
Even the more secular Shia hold him in high regard.
And in any case the idea of standing up to the Americans - on such a universally upheld principle as electoral democracy - has wide appeal.
For the Kurds of the north the rallying-cry is federalism - not some vague formula for devolved power, but an autonomous Iraqi Kurdistan including Kirkuk, a city in an oil-rich region and with a mixed and restive population of Kurds, Arabs and Turkmen.
The Kurds, like the Shia, seem in uncompromising mood.
The country's other main community - the Sunni Arabs - are watching this communal muscle-flexing with undisguised alarm.
Once the political elite, they now fear marginalisation - and a group of their religious leaders has now formed a council to defend Sunni interests.
No-one can be sure where all these political pressures are leading.
But as the Americans try to keep to their 1 July deadline, while struggling to reduce the number of attacks on their forces, the political temperature seems certain to rise.