And as the movement is prone to do, Mr. Sadr again sought to have it both ways in the 28-minute address, calling for the expulsion of American troops but giving time for a withdrawal and offering support for a government his followers underpin but making his backing conditional on that government’s effectiveness.

“We are with it, not against it,” said a grayer Mr. Sadr, who spoke forcefully and deliberately, if occasionally testily, with a confidence he once lacked. “The government is new, and we have to open the way for it to prove it will serve Iraq’s people.”…

In the clearest terms, he insisted no American troops could remain by 2012, as required by agreement, and urged his followers to persist in resistance by any means to their presence. More cautiously, he suggested he could withdraw their support for Mr. Maliki if the government fails to address the most basic complaints of daily life here, particularly for the disenfranchised he claims to represent — shoddy roads, dirty water, leaking sewage and, that motif of post-Saddam Hussein Iraq, persistent blackouts…

At Saturday’s speech, the movement sought to convey a certain respectability, from sharply dressed security in gray suits to the punctuality of Mr. Sadr himself, whose speech began precisely at a scheduled 10 a.m. Cadres passed out Iraqi flags, soon overwhelming the crowd’s pious banners and portraits of Mr. Sadr. In fact, it was hard not to draw at least superficial comparisons to another Arab Shiite movement, Lebanon’s Hezbollah, both of whom navigate political, social and military identities and have built personality cults around their leaders, junior clerics more prominent as politicians.