The committee, which drafted the constitution, presented it to the National Assembly, without the endorsement of Sunni members.
Iraqi President Jalal Talabani says he remains optimistic that Iraqis will approve the charter, following more than two months of intense negotiations between delegates from the country's Shi'ite, Kurdish, and Sunni Arab communities.
Sunday, Sunni negotiators delivered a joint statement rejecting the constitution.
They called the final version "illegitimate," and asked the Arab League, the United Nations, and other international organizations to intervene to block it.
In Saddam Hussein's hometown of Tikrit, thousands of Sunni demonstrators rallied against the constitution Monday.
At least 2,000 protesters assembled near the office of the Association of Muslim Scholars, a hard-line Sunni clerical group opposed to the U.S. occupation of Iraq.
In Washington, U.S. President George Bush expressed disappointment that Sunnis did not endorse the charter, but praised the work of the committee in finally presenting a constitution to the National Assembly after missing several deadlines. "Their example is an inspiration to all who share the universal values of freedom, democracy, and the rule of law," he said.
Sunnis oppose federalism, fearing it could divide the country between a predominately Kurdish Iraq in the north and a Shia Iraq in the south, and deprive Sunnis located in those areas.
They also do not want Saddam's Baath political Party outlawed, fearing widespread purges of Sunnis from government jobs.