BAGHDAD — Dozens of Iraqi legislators walked out of parliament Thursday to protest parts of a draft law that would lay out rules for provincial elections later this year, marking another potential setback for U.S.-backed proposals to ease Iraq's sectarian rifts.

Radical Shiite cleric Muqtada al-Sadr, meanwhile, warned his fighters to stick with his cease-fire order after U.S. and Iraqi raids in Baghdad's Sadr City, the main Shiite district and bastion of al-Sadr's Mahdi Army militia. The sweeps detained 15 suspected militants and left one person dead.

The U.S. military said troops targeted "criminal elements" responsible for attacks with mortars and powerful roadside bombs that the Pentagon links to Iranian aid.

In parliament, the walkout postponed a planned vote on the measure on redistributing power in Iraq.

The last time Iraqis voted for local officials was January 2005, when nationwide elections ushered in representational government across Iraq for the first time in modern history.

But many Sunni Arabs boycotted the polls, giving Iraq's majority Shiites and minority Kurds a much bigger share of power. The U.S. hopes the new elections will empower the Sunni minority and blunt support for the insurgency.

The draft law, if approved, would set an Oct. 1 date for provincial elections, according to a copy obtained by The Associated Press. It is among 18 U.S.-endorsed "benchmarks" seeking to promote reconciliation among Iraq's main groups.

The main sticking point Thursday was a dispute over whether the authority to fire provincial governors should rest with the prime minister or with the councils that govern Iraq's 18 provinces.

Nearly 90 members of the largest Shiite party, the Supreme Islamic Iraqi Council, and its Kurdish allies stormed out of the session after lawmakers approved giving the power to the prime minister. Voting on the rest of the 56-point package was scheduled to resume Saturday.

The Kurds also were upset about a proposal that would allot only about 14.5 percent of the 2008 budget to their semiautonomous region in northern Iraq, instead of the 17 percent they had demanded.

Only one of the U.S.-backed benchmarks have made it into law: a measure that allows lower-ranking members of Saddam Hussein's Baath party to reclaim government jobs. Sunnis, however, have demanded amendments, and the future of the measure is unclear.

Other proposals, including divvying up the country's vast oil wealth and amending the constitution, also remain stalled.

The U.S. military and Iraqi witnesses offered conflicting details about the raid in Sadr City.