Calls emerged within the Shiite alliance Saturday for Prime Minister Ibrahim al-Jaafari to step aside as the bloc's nominee for another term as pressure mounted against him from Sunni Arab and Kurdish politicians.

The political maneuvering came as violence continued to rock the country, with gunmen attacking a minibus carrying Shiites northeast of Baghdad late Friday, killing six men and wounding one woman.

At least 18 other people were killed elsewhere, including three ice cream vendors and a butcher, many in drive-by shootings.

One prominent Shiite politician, former Minister of State for National Security Qassim Dawoud, openly called for al-Jaafari to withdraw his candidacy.

Shiite officials, speaking on condition of anonymity because of the sensitivity of the issue, said others within the Shiite alliance were open to replacing al-Jaafari. But they denied media reports that the Shiite alliance already had asked him to step aside.

"There is a current (within the Shiite alliance) that is calling on the prime minister to withdraw his nomination because the political process has reached a deadlock," Dawoud told The Associated Press. "I personally asked that he withdraw his nomination."

The calls came a day after U.S. Ambassador Zalmay Khalilzad urged the Iraqis to speed up the talks on forming a new government, nearly four months after parliamentary elections were held.

"The terrorists are seeking to provoke sectarian war, and Iraq needs a government of national unity in the face of this threat," Khalilzad told a meeting of Iraqi women. "This government needs to have a good program to govern from the center, and needs good ministers who are competent.

"Iraq is bleeding while they are moving at a very slow pace," he said.

Meanwhile, former hostage Jill Carroll arrived in Germany under U.S. military protection, the first stop on her return to the United States from Iraq where the journalist spent 82 days in captivity.

Gone was the Islamic headscarf she had worn as a hostage and she had traded her full-length robe for jeans, a bulky gray sweater, and a desert camouflage jacket.

"I'm happy to be here," the 28-year-old freelancer for The Christian Science Monitor told Col. Kurt Lohide, the U.S. officer who welcomed her to Ramstein Air Base.

The Shiites were ambushed Friday night near Balad Ruz, 45 miles northeast of Baghdad, as they were returning home from visiting relatives, the town's mayor, Mohammed Maarouf, said.

The motive for the attack was unclear. However, it occurred in a religiously mixed province which has recorded numerous acts of violence by Shiite and Sunni Arab extremists against members of the rival communities.

Tension between the rival Shiite and Sunni Muslim communities escalated following the Feb. 22 bombing of a Shiite shrine in Samarra and reprisal attacks on Sunni mosques in Baghdad, Basra and other mixed cities.

Gunmen also killed three ice cream vendors in the capital's southern neighborhood of Dora, while a butcher and his son were killed and another son was wounded in east Baghdad, police said.

In the western Iskan neighborhood, gunmen killed the owner of an air conditioner repair shop on his way to work. A Sunni sheik was killed by gunmen in a speeding car when he left his home in the southern city of Basra. His brother, who was with him, was wounded, a Sunni official said.

Police reported the discovery of at least seven bodies, mostly young men who were shot in the head or strangled in Baghdad — the latest apparent victims of sectarian death squads. Witnesses also told police they saw three gunmen in a BMW pull a handcuffed man out of the car and shoot him near a highway in west Baghdad.

West of Baghdad, U.S. and Iraqi troops killed three suspected insurgents, including a woman, and captured three others Saturday in an operation in Amiriyah in Anbar province, the U.S. military said.

South of Baqouba, an Iraqi army sergeant major was killed Friday after his patrol surprised a group of suspected insurgents trying to steal a dump truck, the U.S. military said.

Four of the insurgents were killed in the firefight, and the rest detained, while weapons near the area were seized, a statement said. Four Iraqi soldiers were also wounded.

In Basra, Iraq's second-largest city, a joint British-Iraqi force detained 14 people, including a policeman, in a dawn raid in two neighborhoods, Brig. Patrick Marion said. Four detainees were later released, Marion said.

Opposition to al-Jaafari, a former physician who spent years in exile in Iran and Britain, has bogged down talks among Shiite, Sunni and Kurdish politicians over formation of a new national unity government following the Dec. 15 elections.

U.S. officials are pressing the Iraqis to move quickly to set up such a government to curb the violence and pave the way for U.S. and other coalition troops to begin heading home.

Sunni and Kurdish politicians claim al-Jaafari's government had been ineffective in curbing tensions between Shiite and Sunni Muslims. Al-Jaafari won the nomination by one vote in a caucus of Shiite lawmakers last month

Al-Jaafari edged out Vice President Adil Abdul-Mahdi because of support from radical Shiite cleric Muqtada al-Sadr. The prospect of a prime minister politically beholden to the vehemently anti-American al-Sadr has alarmed both Iraqi and U.S. officials.

On Saturday, al-Sadr's bloc in parliament reaffirmed its support for al-Jaafari.

"We will not abandon our decision regarding al-Jaafari's candidacy," the bloc's leader in parliament, Salam al-Maliki, told Al-Arabiya television.

Under the constitution, the nominee of the biggest bloc in parliament gets first crack at the prime ministership, subject to parliamentary approval. The Shiites control 130 seats in the 275-member parliament. That's enough to claim the top government post but not enough to govern without coalition partners.