More sectarian fighting broke out Monday after efforts to form a unity government suffered a new setback. Leaders again failed to agree on a prime minister and postponed a parliament session to give the religiously and ethnically based parties more time to negotiate.

Four Marines were reported killed in fighting west of Baghdad, bringing the U.S. death toll for this month to 47 ¡ª compared with 31 for all of March.

At least one Iraqi civilian was killed and seven were wounded Monday in a gunbattle in northern Baghdad, while a series of bombs killed at least two people in Baghdad and the city of Baqouba.

U.S. officials believe the best way to stem the violence is for the Iraqis to establish a government composed of Shiites, Sunnis and Kurds, paving the way for the United States to start withdrawing its 133,000 troops.

But progress has stalled over Sunni and Kurdish opposition to the Shiite choice of Prime Minister Ibrahim al-Jaafari to head the new government. With al-Jaafari refusing to step aside, acting speaker Adnan Pachachi called a parliament session for Monday, hoping the full legislature could agree on a new leadership after the politicians failed.

On the eve of the session, Pachachi announced a delay of "a few days" to give the parties more time to agree on the new prime minister, president and five other top posts that require parliamentary approval.

Before the announcement, Shiite official Hussain al-Shahristani told Sunni and Kurdish leaders that his bloc, which controls 130 of the 275 parliament seats, would decide what to do about al-Jaafari "within the coming two days," Kurdish lawmaker Mahmoud Othman said.

Voters chose the new parliament on Dec. 15, but the legislature met briefly only once last month.

Pressure has been mounting on the Shiites to replace al-Jaafari, whom critics accuse of failing to curb sectarian tension that has soared since the Feb. 22 bombing of a Shiite shrine in Samarra, which triggered a wave of reprisal attacks against Sunnis.

In an interview Sunday on CNN's "Late Edition," Iraq's ambassador to the United States, Samir Sumaidaie, said Shiite lawmaker Ali al-Adeeb had emerged as a possible prime minister candidate. Al-Adeeb is a member of al-Jaafari's Dawa party but spent many years in Shiite-dominated Iran ¡ª which could cause problems with the Sunnis.

The Shiites, however, are maneuvering carefully because they suspect the Sunnis and Kurds want more of a role in the new government than they would be entitled to based on their showing in the December election.

Al-Jaafari won the nomination in a vote last February by Shiite lawmakers ¡ª thanks to strong support from radical anti-American cleric Muqtada al-Sadr. The cleric, who heads the dreaded Mahdi Army militia, has vowed to stand behind the incumbent.

With little progress on the political front, Iraq's slide toward chaos continued.

Four Marines ¡ª three from Regimental Combat Team Five and one from the 2/28 Brigade Combat Team ¡ª died Saturday in Anbar province, the U.S. command said Sunday.

Their deaths raised to at least 2,376 the number of U.S. military members who have died since the war began in March 2003, according to an Associated Press count. The rise in U.S. casualties followed a sharp drop in March, which saw the lowest number of American dead in Iraq since February 2004.

A gunbattle erupted between insurgents and the Iraqi army early Monday in Azamiyah, a mostly Sunni Arab neighborhood of Baghdad, killing at least one civilian and wounding seven, hospital officials said.

A series of bombs exploded in Baghdad and the city of Baqouba, killing at least two people and wounding more than 15.

A roadside bomb targeted an army patrol in central Baghdad, killing a civilian and wounding nine, including some soldiers, police said. The explosion of a bomb hidden in a garbage can near a market in New Baghdad wounded at least four civilians, and a roadside bomb wounded one policemen in eastern Baghdad, officials said.

In central Baqouba, 35 miles northeast of Baghdad, a roadside bombing near a medical clinic killed one civilian and wounded two others, police said.

Gunmen in the southern city of Basra kidnapped three employees of a state-run electrical company on their way to work. The body of a Basra policeman kidnapped three days earlier was found near the Iranian border, Basra police Capt. Mushtaq Khazim said.

Also near Basra, gunmen attacked a convoy carrying the deputy culture minister, who was attending a poetry festival in the region. His bodyguards exchanged fire with the assailants but there were no casualties, a ministry spokesman said.

Back in Baghdad, police discovered three bodies of blindfolded and handcuffed men in the mostly Shiite Arab neighborhood of Shula. Assailants attacked a police patrol in western Baghdad in a drive-by shooting, wounding two policemen, police said.