BAGHDAD, Iraq — Prime Minister Ibrahim al-Jaafari canceled a meeting today with Iraq's top political leaders after they agreed to mount a campaign to deny him another term in a bid to jump-start stalled talks on a new government.

Al-Jaafari had called the meeting to discuss ways to resolve the political standoff and contain a surge of sectarian killing that pushed Iraq to the brink of civil war.

Violence claimed at least 31 more lives today. Among the bloodiest attacks were the bombing of a vegetable market in a mostly Shiite section of Baghdad and an assault on an Iraqi checkpoint north of the capital.

Gunmen also attacked the car of a top Sunni Muslim political leader, killing one bodyguard and wounding five. Adnan al-Dulaimi, a leader of the Sunnis' largest parliamentary bloc, had already sped away in another vehicle after his car was stopped by a flat tire, said Yassir al-Obeidi, a spokesman for his conference of the People of Iraq party.

The talks on a new government broke down last week when Sunni parties pulled out in protest against attacks on Sunni mosques triggered by the Feb. 22 bombing of a sacred Shiite shrine in the central city of Samarra. Hundreds were killed in the sectarian fury that followed.

They included 45 Sunni preachers and mosque employees, according to Sheik Ahmed Abdul Ghafour al-Samaraie, head of the government's Sunni Endowment, which takes care of Sunni mosques and religious shrines.

Yet another Sunni cleric was gunned down as he left a mosque after dawn prayers this morning in Basra, in the southern Shiite heartland. It was not clear if the cleric was included in al-Samaraie's count.

As violence surged last week, the U.S. 2nd Brigade, 1st Armored Division was put on alert in neighboring Kuwait for a possible move into Iraq, the military said. But no such orders were given.

The sectarian killing has eased since then, but bloodshed continues.

The violence has complicated talks to form a broad-based government, which U.S. officials consider essential to lure Sunni Arabs away from insurgents so coalition forces can start drawing down later this year.

Al-Jaafari's office gave no reason for calling off today's meeting with major political parties.

On Wednesday, leaders of three parties, including Sunnis, Kurds and the secularists of ex-Prime Minister Ayad Allawi, agreed to ask the main Shiite bloc to withdraw al-Jaafari's nomination for prime minister and put forward another candidate. Officials of all three groups confirmed the plan but spoke on condition of anonymity because of the sensitivity of the subject.

The Shiites won 130 of Parliament's 275 seats in December elections, giving them the largest bloc of lawmakers and the first chance to form a government — but not enough to govern without partners.

Al-Jaafari won the nomination by a single vote in a Feb. 12 ballot among Shiite lawmakers.