BAGHDAD - Anti-American cleric Muqtada al-Sadr, whose power once seemed all but crushed, has made a remarkable political resurgence in Iraq's parliamentary elections. The Iran-based Shiite leader is now poised to play a key role in choosing Iraq's next prime minister.

He may use his newfound clout to push his archenemy, Nouri al-Maliki, from power.

Sadrist support is crucial for al-Maliki as he tries to assemble enough Shiite backing to remain prime minister. But the young cleric is holding a referendum among his supporters Friday and Saturday to decide whom to support for the post. The move is widely viewed as a way to give himself the opportunity to back someone other than al-Maliki, under the guise of following the people's will.