Iraq's Cabinet will vote Sunday on a security pact with Washington that would keep U.S. forces in the country for another three years, a major step in efforts to balance Iraqi demands for national sovereignty with the security concerns of the two allies.

The accord goes before the Cabinet, with the most powerful cleric in Iraq, Grand Ayatollah Ali al-Sistani, signaling that he would not object to it.

A senior official at al-Sistani's office said the cleric told two legislators that the document represented "the best available option" for Iraq, signaling that he would not oppose it if the Cabinet and later parliament approve it.

The official, who spoke on condition of anonymity because of the sensitivity of the subject, said al-Sistani indicated to Khalid al-Attiyah and Ali al-Adeeb that he wanted the agreement to pass by a comfortable majority in the 275-seat parliament.

Prime Minister Nouri al-Maliki on Saturday dispatched the two senior lawmakers to see al-Sistani in the holy city of Najaf, south of Baghdad, in a bid to secure support for the agreement.

Al-Sistani commands enormous influence with Iraq's majority Shiites. The Iranian-born cleric does not speak to reporters, communicating his views through edicts or leaks from his office. His public silence on a major policy decision is often taken to mean he has no objections.

Al-Attiyah said al-Sistani had stressed the need for "national accord" over the agreement. Al-Adeeb said "His eminence, al-Sistani, is comforted by the thoroughness of Iraqi officials who shoulder the responsibility of safeguarding national interests."

The U.N. mandate covering the presence of U.S. and other foreign forces in Iraq expires Dec. 31, and failure to pass the agreement would leave Iraq with little choice but to seek a renewal of the mandate.

A series of bombings Saturday pointed to the fragility of security gains in the past year. The violence also was likely to strengthen the argument of the pact's proponents, including the interior and defense ministers, that there is still a need for U.S. forces.

In Tal Afar, a suicide car bombing struck a commercial district, killing nine Iraqis and wounding 40, according to the U.S. military. Iraqi police and hospital officials said seven people were killed and up to 32 were wounded. There was no immediate explanation for the discrepancy.

In Baghdad, a bomb in a parked car exploded near the National Theater in the mainly Shiite district of Karradah, killing at least five and wounding 23, according to police and hospital officials. Some victims were heading to the theater to see a political satire, said the officials, speaking on condition of anonymity because they were not authorized to release the information.

The U.S. military, however, said initial reports indicated no deaths but 19 civilians wounded in the Baghdad bombing. It also said a suicide bomber in a vehicle in the northern city of Mosul injured 13 Iraqis on Saturday, and that a U.S. Marine died from wounds suffered in a roadside bombing west of Baghdad on Friday.

Also Saturday, two American soldiers died when a helicopter made a "hard landing" after hitting wires in Mosul, the U.S. military said. It said the OH-58 Kiowa Warrior helicopter went down because of an accident and that there was no enemy fire in the area.

Mosul is a flashpoint of insurgent activity that has defied stepped up efforts by U.S. and Iraqi forces to bring stability. The attacks Saturday raise questions about the preparedness of Iraqi forces and back assertions by proponents of the security pact that they still need American help.

A close aide to al-Maliki and two Cabinet ministers said Iraqi and U.S. negotiators have agreed on a final draft of the security pact and that it would be put to a vote in an emergency Cabinet meeting Sunday.

The aide, speaking on condition of anonymity because of the sensitivity of the subject, said the pact stood "a good chance" of being passed by a two-thirds majority in the 37-member Cabinet and that the final draft was reached after "intense" contacts between the American and Iraqi sides.

In Washington, National Security Council spokesman Gordon Johndroe described the final document as beneficial to the allied nations.

"We think this is a good document that serves both Iraqis and Americans well," he said. "We remain hopeful that the Iraqi government will conclude this process soon."

Al-Attiyah, one of the Shiite lawmakers who met al-Sistani, told reporters in Najaf that the Americans have agreed to two changes proposed by al-Maliki. One of the two, he said, removed a phrase that could delay the withdrawal of U.S. forces from Iraqi cities and back to bases in outlying areas by the end of June.

He did not mention the second change. Iraq has demanded guarantees for its right to try U.S. soldiers and defense contractors for serious crimes committed off-duty and off-base and to ensure that the United States does not use Iraqi territory to attack a neighboring country, such as Iran or Syria.

It also wanted stronger language to clarify that U.S. troops cannot stay in Iraq after Dec. 31, 2011.

If the Cabinet passes the draft agreement Sunday, the 275-seat parliament could follow suit because the political blocs in al-Maliki's government dominate the legislature. The agreement needs a simple majority to pass in parliament.

The final step would be ratification of the deal by President Jalal Talabani and his two vice presidents.

Most political parties have been reluctant to state their position on the pact, fearing a voter backlash in key provincial and general elections in 2009 and the stigma of being seen as condoning the presence in Iraq of U.S. forces who are viewed as an occupation army.

Some, including al-Maliki's senior partner in the government, looked to al-Sistani for political cover, saying they would only sign off on the agreement if the cleric backed it. Shiite leader Muqtada al-Sadr, whose militiamen fought U.S. forces in three uprisings since 2003, has threatened to renew attacks on the Americans if they don't immediately begin to withdraw from Iraq.

The only major group that supported the pact from the start was the Kurdish bloc, America's most reliable ally in Iraq. The Kurds look to Washington as the guarantor of their self-ruling enclave in northern Iraq.