From the Washington Post today:

“Sadr has appealed to poor and disenfranchised Shiites, the majority of Iraq’s population, with a relentless anti-occupation message. A junior cleric, the 30-year-old’s authority is far overshadowed by Grand Ayatollah Ali Sistani, the country’s leading religious figure. Sadr and his followers remain distinctly unpopular in the Shiite holy city of Najaf [emphasis added], where the more established clergy hold sway.”