BAGHDAD, Iraq — Iraq's war-battered voters apparently approved a new constitution in voting Saturday, preliminary and unofficial results showed yesterday, but disaffected Sunni Arabs proved unexpectedly formidable in their first venture into post-Saddam Hussein politics with a strong vote against the U.S.-backed charter.

Province-by-province tallies yesterday showed the constitution winning approval in Saturday's voting with the unified backing of Iraq's Shiite Muslim and Kurdish communities, who together are about 80 percent of the country's population. Sunni Arabs, who account for about 20 percent of Iraq's people, apparently did not muster enough votes to defeat the measure, which required rejection by two-thirds of voters in at least three of Iraq's 18 provinces.

According to electoral officials in four crucial battleground provinces where Sunni Arabs had the popular strength to potentially defeat the constitution, voters rejected it in two provinces — Salahuddin, with an 81 percent vote against, and Anbar, where an even larger vote against the constitution was expected. The Sunnis missed their goal in the other two — Diyala and Ninevah — despite spirited contests, electoral officials said.

Authorities gave differing numbers for total turnout but agreed it topped 60 percent.

Political violence yesterday remained below the level of recent months.

Hospital officials in Ramadi alleged 25 people were killed when U.S. warplanes retaliated for a roadside bombing yesterday. The planes attacked as bystanders gathered around a U.S. Humvee as it smoldered on the side of the road, said Khalid Alwani, an official at Ramadi hospital.

As early tallies from the constitutional referendum emerged yesterday, some Sunni leaders cried foul, saying their field surveys showed they had crossed the threshold for defeating the proposal. They charged the government, a coalition of Shiite and Kurdish parties whose leaders dominated the drafting of the constitution, was stealing the election.

What's next

If charter is approved: Iraqis would choose a new parliament in national elections to be held by Dec. 15. Parliament then would select a new government, which would have to take office by Dec. 31. The new administration would be Iraq's first permanent, fully constitutional government since the collapse of Saddam Hussein's rule in 2003. Sunni Arabs have been promised they can propose constitutional amendments in the first four months of the new parliament. Amendments would need two-thirds approval in parliament and voter support in a referendum.

If charter is rejected: Parliament would dissolve but mid-December elections would go ahead as planned. New parliament would have to draft another constitution within a year and present it to voters in second referendum. Interim constitution approved in March 2004 would continue as legal foundation for governing Iraq.

The Associated Press

"I believe they will rig the results and announce the success of the referendum, but our monitors reported to us that more than 80 percent of the voters in three governorates have said no to this draft," said Saleh al-Mutlaq, a spokesman for the Sunnis' National Dialogue Council. (Iraq's provinces are formally called governorates.) "This constitution is a menace to the unity and stability of Iraq, and we shall have no legal or legitimate means in order to defeat it."

Saadoun Zubaidi, an independent Sunni member of parliament who worked on drafting the constitution, said independent monitors had concluded Sunnis turned back the referendum in at least three and possibly four provinces, "but if you want to fiddle with it, that's a different matter." If the results need to be contested, he said, "we'll do it through the channels."

Adil Lami of Iraq's electoral commission said the commission had received no formal complaints of fraud, adding that "launching accusations in advance" was a tactic typically used by people who felt results were not going their way. "The whole process was successful, and the electoral commission succeeded in holding an honest and transparent referendum," he said.

U.S. officials and their allies, including Iraqi government officials, had hoped the larger-than-expected Sunni turnout heralded their return to mainstream politics in Iraq and disavowal of the 2-year-old insurgency. Sunni Arabs, who ruled here for decades and wielded extraordinary authority under Saddam, lost power after U.S. and coalition forces toppled him two years ago. They boycotted legislative elections in January, and Sunni extremists have been the backbone of the insurgency. Almost 2,000 U.S. soldiers have died here since the 2003 invasion.

In Washington, President Bush praised Iraqis for successfully holding the referendum. "This is a very positive day for the Iraqi people and, as well, for world peace," he said. "Democracies are peaceful countries."

Secretary of State Condoleezza Rice said initial assessments indicated Iraqis had probably approved the constitution, although she said the turnout alone proved the fragile new political process has taken hold.

"The general assessment is it will probably pass," Rice said. "I think that the assessment of the people on the ground, who are trying to do the numbers and trying to look at where the votes are coming from, is there's a belief that it can probably pass. But again, we'll see."

Washington Post reporters Robin Wright, Omar Fekeiki and Dlovan Brwari contributed to this report.