Efforts to form a national unity government in Iraq apparently suffered another setback Thursday, when plans to announce the next session of parliament were canceled.

New reports from Baghdad say Shi'ite leaders opposed convening parliament next week. Sunni and Kurdish leaders were hoping the 275-member legislature could meet to decide the future of Prime Minister Ibrahim al-Jaafari.

The prime minister has refused to give up his candidacy to lead the country's next government, despite calls to step aside from within his Shi'ite coalition as well as the West.

Some Shi'ite politicians are indicating they might seek the advice of the country's most respected Shi'ite cleric, Grand Ayatollah Ali al-Sistani.

The Jaafari candidacy is one of the main sticking points that has deadlocked efforts to form a national unity government in Iraq nearly four months after parliamentary elections.

U.S. Secretary of State Condoleezza Rice and British Foreign Secretary Jack Straw visited Baghdad earlier this week to press for the formation of a government as soon as possible.

President Bush also urged Iraqi politicians to form a government without further delay. He said every day of delay is another day of violence in the war-torn country.

Some information for this report was provided by AP and Reuters.