But Sunni Arab politicians were pessimistic of reaching a deal by the Monday deadline, with one, Saleh al-Mutlaq, saying discussions "need divine intervention."
Iraq's three major Sunni organizations appeared to have taken a united stand both for voting and against demands for federalism after they boycotted the Jan. 30 parliamentary elections.
Sunni delegates continue to oppose autonomy for the Kurdish north, fearing the breakup of the country, CBS News Correspondent Tom Popyk reports.
The Kurdish minority has demanded federalism be enshrined in the constitution to protect the regional self-rule it has enjoyed in the north since 1991. Many Sunni Arabs, a formerly dominant minority, oppose federalism, fearing it would lead to the breakup of Iraq.
Mahmoud Othman, a Kurdish legislator, said late Friday that Shiites and Kurds have agreed that the country be called the Iraqi Federal Republic and that Islam be the religion of the state. Kurds from Kirkuk would receive compensation or be permitted to return to city, Othman said.
In other developments:
Popyk adds that responsibility for the deaths are pitting residents against U.S. marines. Residents say a roadside bomb detonated beside a U.S. patrol in Ramadi, just after prayers Friday. Then witnesses say, in the chaos, troops began to fire indiscriminately into crows leaving a nearby mosque.
A marine spokesman fiercely denies any troops fired at civilians, but wouldn't confirm the patrol was attacked. The director of Ramadi's hospital say the dead included eight children.
The blast Friday occurred on the outskirts of the town of Nasaf, near Ramadi, an insurgent center 70 miles west of Baghdad, according to police Lt. Mohammed al-Obeidi and Dr. Mohammed al-Ani of Ramadi General Hospital.
A hospital official, Ali Taleb, said a U.S. armored vehicle fired near the Ibn al-Jawzi mosque, about 15 miles east of Ramadi, after worshippers left the building following Friday prayers.
Othman said Shiites and Kurds, who hold majority seats in parliament, had offered concessions to each other, but said disagreements with Sunni Arabs had been more difficult to resolve.
Other major issues remained unresolved, such as the role of Islam in state laws and how the government should distribute the country's wealth.
During a speech Thursday to cheering crowds in the city of Najaf, Abdul-Aziz al-Hakim, leader of the country's biggest Shiite party, called for a Shiite federal state, saying it was needed "to keep a political balance in the country" after decades of dictatorship under Saddam Hussein.
Al-Hakim's comment drew a strong response from Sunni clerics throughout Iraq during Friday sermons. The clerics urged followers Friday to register and vote against a constitution that enshrines federalism.
At the Kmeira Mosque in Baghdad's northern neighborhood of Rashdiyah, about 500 Sunni Arabs gathered to listen to Sheik Ayad al-Izzi say "we reject these calls (for federalism) and we look to them with suspicion."
Al-Mutlaq, a Sunni member of the constitution drafting committee, said he and the other Sunnis have told the Shiites and the Kurds that if they put federalism in the constitution, "it will be rejected by the people."
Sunnis were preparing their people to go out and vote, in contrast the Jan. 30 elections. Sunnis largely stayed away from that vote, fearing insurgent attacks or heeding boycott calls by rebels and hard-line clerics.
"We call our sons to go out and register their names so that they can take part in the coming referendum on the constitution and the general elections," Sheik Fakhri al-Qaisi told a congregation in Saddam Hussein's hometown of Tikrit, 80 miles (129 kilometers) north of Baghdad.
Al-Qaisi told worshippers at Tikrit's Grand Mosque that "we should all go out and vote."
Sheik Mahmoud al-Sumaidaie, of the influential Association of Muslim Scholars, told worshippers at Baghdad's Umm al-Qura mosque to register for the referendum and the Dec. 15 general elections because "we are in need to your voice to say 'yes' for the constitution or 'no'."
"We, in this country, don't want federalism because we are a unified nation in this country and we feel that Iraq with all it's elements is for all" of us, al-Sumaidaie said.
The move by the Sunnis comes three days before a deadline for the constitution to be handed to parliament by the drafting committee. Shiite, Sunni and Kurdish political leaders have been discussing several points of disagreement, including federalism, for days.
The Sunnis appear to be sending a warning that they can bring down the constitution in the Oct. 15 referendum. According to the country's interim charter, the constitution will be void if it is rejected by two-thirds of voters in three provinces.
Sunnis are a majority in the provinces of Anbar, Salahuddin, Ninevah and Diyala.
Al-Izzi, of the Kmeira Mosque, said "don't sit at home because by staying at home it means you are accepting. We will say no to anything that contradicts with our religion and we will say no to anything that leads to splitting the country."