This is a development I have been expecting for some time. The longer Muqtada al Sadr remained outside the political sphere and used his Mahdi Army militia to attack the Iraqi security forces and government, the greater the pressure became for the government to ban his political party and militia. The fighting in Basra has shown that Sadr and his movement/militia are now anti-state elements, and the disparate political parties are seeking to pressure Sadr to disband his Madhi Army or face being banned from political activity. Per the AP:

Iraq's major Shiite, Sunni and Kurdish parties have closed ranks to force anti-American cleric Muqtada al-Sadr to disband his Mahdi Army militia or leave politics, lawmakers and officials involved in the effort said Sunday...

The first step will be adding language to a draft election bill banning parties that operate militias from fielding candidates in provincial balloting this fall, the officials and lawmakers said. The government intends to send the draft to parliament within days and hopes to win approval within weeks.

"We, the Sadrists, are in a predicament," lawmaker Hassan al-Rubaie said Sunday. "Even the blocs that had in the past supported us are now against us and we cannot stop them from taking action against us in parliament."

Everyone rushed to declare the Maliki government defeated and neutered after the Basra operation hit a speed bump in its opening phase. But the push to force Sadr to disband his Mahdi Army or face the political wilderness suggests otherwise.