BAGHDAD, Iraq - Iraq's head of parliament announced Saturday that Shiites and Kurds had agreed to Sunni Arab proposals for the new constitution and were awaiting a response. But Sunni negotiators said the changes fall short of their demands and urged voters to reject the draft in the Oct. 15 referendum.

Speaker Hajim al-Hassani, himself a Sunni, said the amended text, dealing with issues of federalism and former members of Saddam Hussein's Baath Party, would be submitted today to parliament. The legislature, overwhelmingly Shiite and Kurdish, may vote on it or simply refer it to the voters.

Al-Hassani's comments followed similar statements late Friday by Shiite and Kurdish lawmakers but were significant because he has final say in when the assembly will act.

His remarks indicated that negotiations on the new constitution had run their course. Barring a sudden change of mind by the Sunnis, the charter is likely to go to the voters over Sunni objections, setting the stage for a bitter political battle ahead of the referendum by supporters and opponents of the draft.

If the constitution clears parliament without Sunni blessing, it would be a blow to the Bush administration, which insisted all along that Sunni participation was critical to produce a document which was accepted by all communities.

Sunni Arabs are at the forefront of the insurgency and the Americans hoped the constitution would lure them away from the rebellion. But Sunni negotiator Saleh al-Mutlaq said the final draft fails to meet Sunni aspirations.

"We tell our people that we have fulfilled the duty that you asked us to do," al-Mutlaq told reporters Saturday. "We have sincerely done the job and now the matters are up to you. We want those who did not wake up until now to wake up. We want you to express your point of view but without violence" in the Oct. 15 referendum.

Written versions of the Shiite-Kurdish concessions were not released.

But Al-Hassani said the concessions, which were presented to the Sunnis on Friday, involved delaying details how to implement federalism - or the establishment of self-ruled regions - until a new parliament is elected in December - presumably with more Sunni members than the current one.

On the issue of purging former Baath Party members, many of them Sunnis, al-Hassani said "not every person who joined the Baath Party is a criminal. There are hundreds of thousands of people who joined the Baath Party for a reason or another and they come from all regions."

The vast gulf among Iraq's communities made the task of drawing up a document acceptable to all difficult. In a bid for consensus, President Bush telephoned a top Shiite leader, Abdul-Aziz al-Hakim, and asked him to make compromises with the Sunnis.

"A parliamentary agreement has been reached between the Kurdish coalition and the (Shiite) alliance on accepting the suggestions of the forces that did not take part in the elections (Sunnis) and it will be announced in parliament tomorrow," al-Hassani said.

Meanwhile, in an apparent attempt to mollify Sunni Arabs, the U.S. military on Saturday announced the release of nearly 1,000 security detainees from Abu Ghraib prison over the past several days.

The move, which had been in the works for some time, was the largest prisoner release to date and followed appeals by Sunni negotiators to the government to set free thousands of prisoners - most of them Sunnis - who have been languishing in the jail for months without being charged.