Already pressured by the U.S. withdrawal from the nuclear deal, Iran faces a major test in managing Shiite cleric Moqtada al-Sadr, a formidable opponent who beat Tehran's longtime allies to achieve a shock victory in Iraq's parliamentary election.
But if Tehran overplays its hand by squeezing al-Sadr out of a coalition government dominated by its allies, it risks losing influence by provoking conflict between Iranian-backed Shiites and those loyal to al-Sadr.
He swept Iraq's parliamentary election by tapping into growing public resentment directed at Iran and what some voters say is a corrupt political elite that has failed to help the poor.