According to Strategy Page, Moqtada al Sadr needs to make up his mind pretty quickly, whether his Mahdi Army should fight on and die, or surrender and hope for amnesty.
Over the last five years, the Shia militias, especially the Mahdi Army, have gone from a neighborhood protection (from Sunni Arab terrorists) force, to a bunch of gangsters. The Mahdi men always demanded support from the people they protected. At first it was just some food and a place to sleep. But as prosperity returned to the area, the demands increased. That prosperity also brought with it a desire for expensive vices, like drugs and prostitution. This split the Shia militias, because some were insisting that everyone lead a life of strict Islamic simplicity. Other Mahdi men would look the other way while you partied, for a price. In the last year, as the Sunni Arab terrorism campaign collapsed, the Mahdi Army lost its last bit of legitimacy. They were now starkly revealed as just another bunch of gangsters. But they were also local guys, with nowhere else to go. To surrender meant the chance of prison, or worse. Fighting to the death didn't seem like such a bad alternative, as long as there was a chance of victory, or surrender with an amnesty. But their leader, Muqtada al Sadr, knows that surrender means a major setback for the Sadr political organization. Sadr has to make up his mind quickly, while there are still Mahdi Army gunmen left willing to fight. Another week or so of fighting, and there won't be.