Baghdad, Iraq ? Rebuffed in the constitution deliberations, Sunni Arabs now face a dilemma: boycott the Oct. 15 referendum on a new charter and hand the Shiites a landslide victory, or take part in a vote that demographics suggest they’ll lose.

But the Shiite community itself is divided over the constitution, and interviews on Baghdad streets indicate the key federalism proposal may be a hard sell to many on both sides.

About 2,000 people, mostly Sunnis, marched Monday against the constitution in Saddam Hussein’s hometown of Tikrit. Some carried pictures of Saddam and repeated chants heard in countless stage-managed protests during his regime: “We sacrifice our souls and blood for you, Saddam.”

Others carried pictures of radical Shiite clerics Muqtada al-Sadr and Jawad al-Khalisi, who have joined the Sunnis in opposing the constitutional draft because of federalism – which critics fear will lead to the disintegration of Iraq.

It seems unlikely that mainstream Sunni Arab leaders will launch an organized campaign to keep Sunnis from the October polls, but their refusal to endorse the constitution was a major setback for the U.S. strategy to lure militant Sunnis away from the insurgency and hasten the day U.S. troops can go home.

The Jan. 30 boycott was widely perceived by Sunnis as a disaster, handing control of the 275-member National Assembly to Shiites and Kurds. The Shiite-Kurd alliance then pushed through demands for federated mini-states and set the legal foundation for purging thousands of Sunni Arabs from government jobs because of past membership in Saddam’s Baath Party.

Residents sign their names in the registration center Monday in Baqouba, 35 miles northeast of Baghdad.

Instead, Sunni Arabs are urging followers to register by the Thursday deadline and reject the constitution in the referendum. Voter registration in the Sunni stronghold of Anbar province was extended for a week so more people could sign up.

The very Sunni clerics who railed last January against an election “under foreign military occupation” are now urging their people to take part in both the referendum and the parliamentary balloting in December.

Rejection of the charter would mean elections in December for a new parliament under the rules of the interim constitution approved in March 2004 and still in effect. The new parliament would start the entire process of drafting a constitution from scratch.

Once the constitution becomes law, it cannot be amended for eight years; under the law now, the draft charter cannot be changed because it has been submitted to parliament.