The Jamestown Foundation's Terrorism Focus, 19 Jun 07:

Moqtada al-Sadr Stepping into the Power Vacuum
...Al-Sadr has much to gain from the current situation. First and foremost, the Iraqi government is arguably at its weakest, especially because the U.S. troop surge has made Iraqi forces more dependent on the United States and less reliable as an independent military entity in the face of a stubborn Sunni insurgency. Second, al-Sadr's political rival, Abdul Aziz al-Hakim of the Supreme Islamic Iraqi Council (SIIC), is undergoing treatment for lung cancer in Iran. Al-Hakim's absence has allowed al-Sadr to fill a political vacuum that positions him as an unrivaled Shiite leader—except in relation to Grand Ayatollah Ali al-Sistani. Third, with a substantial Sunni Iraqi opposition to the government, which is growing as the Shiite-led Nuri al-Maliki government continues to weaken, al-Sadr has found a new constituency that shares his political objectives. This constituency intends to attain the withdrawal of U.S. troops and the establishment of an Islamic state led, or supervised, by clerics and religious institutions. This situation has created a new dynamic that has enabled the young al-Sadr to reenter Iraqi politics as both a reliable alternative to the country's government and a force behind the building of national unity—he seeks the support of the highly disgruntled Sunni Iraqi factions, especially the tribal orders of Anbar province who are highly suspicious of al-Hakim's model of federalism.

Al-Sadr's most recent tactic is to reshape himself as a true Iraqi nationalist. He is now operating on both political and military levels, which reflects his long-term strategic vision for consolidating power, especially in non-Shiite regions....