Updated

The U.S. ambassador held talks with a top Shiite leader Tuesday as Iraqi factions wrangled over a new government. The prime minister declared he would not be "blackmailed" into stepping aside, and the Shiite majority balked at convening the parliament.

The inability to agree is threatening to crush American hopes of beginning a troop pullout this summer as violence rages on. Bombings, mortar blasts and gunfire killed 19 more people throughout the country Tuesday, and police also reported finding four more bullet-riddled bodies — two of them with their eyes gouged out.

On Wednesday, at least 23 bodies — many of them hanged — were found dumped in parts of Baghdad, police said. Eighteen of the bodies were found in an abandoned minibus on a road between two mostly Sunni Muslim neighborhoods in western Baghdad.

Holding a first session of parliament is a required step toward forming a new government. Fifteen days after the first meeting, parliament is supposed to elect a new president — a job the incumbent, Jalal Talabani, wants to keep. In 15 more days, the parliament is to approve the nominated prime minister and 30 days later must vote on his Cabinet.

Underscoring U.S. concerns over the deteriorating political situation, Ambassador Zalmay Khalilzad held a meeting with Abdul-Aziz al-Hakim, head of the powerful Shiite Supreme Council for the Islamic Revolution in Iraq, one of the two dominant parties in the Shiite coalition that won the Dec. 15 parliamentary elections.

The two met at al-Hakim's Baghdad home to discuss "the current political situation concerning the formation of a new government and developments related to the alliance's candidate to head the Cabinet (al-Jaafari)," the SCIRI Web site reported with an accompanying photo of the session.

The U.S. Embassy did not immediately respond to a request for further information.

In an interview published Tuesday, Khalilzad said the 2003 U.S. ouster of Saddam Hussein had opened a "Pandora's box" that could see the violence and turmoil now gripping Iraq turn into an all-out regional war if American troops are withdrawn too quickly.

"We have opened the Pandora's box and the question is, what is the way forward?" Khalilzad told the Los Angeles Times. "The way forward, in my view, is an effort to build bridges across (Iraq's) communities."

But narrowing differences among Iraq's Shiites, Sunnis and Kurds has become an increasingly difficult task in the aftermath of the Feb. 22 bombing that destroyed the golden dome atop a Shiite shrine in the mainly Sunni city of Samarra.

The attack set off two weeks of sectarian revenge attacks, mainly targeting Sunni mosques, clerics and neighborhoods. Sunni politicians have accused the Mahdi Army, the Shiite militia loyal to firebrand cleric Muqtada al-Sadr, of launching many of the attacks with the blessing of the Shiite-controlled government security apparatus.

In a report Tuesday, U.N. Secretary-General Kofi Annan said U.S.-led coalition forces and Iraq's authorities may be violating international law by arbitrarily detaining thousands of people.

The report, which studied the situation in Iraq over the last three months, said Iraq's prison system remains a major concern and lamented that an investigation into allegations of torture in Iraqi Interior Ministry jails had not yet been made public as promised.

Annan's criticism of Multinational Forces and the Iraqi authorities in responding to violence was among the strongest he has made, although many of his claims were not new. He said the detainment of thousands of Iraqis "constitutes de facto arbitrary detention."

Accusations such as those brought by Sunni politicians and echoed by Annan — and the simmering feud between Talabani, the Kurdish president, and Ibrahim al-Jaafari, the Shiite prime minister who owed his re-nomination to al-Sadr's backing — spurred the formation of a coalition determined to block al-Jaafari's second term.

If Kurds and Sunnis refuse Cabinet posts because of al-Jaafari, it could mark a failure of the U.S. goal of setting up a unity government with support of all ethnic and religious factions.

Washington policy holds that such a unity government would inspire sufficient loyalty from all parties to enable it to fight the raging insurgency by itself as American forces began to withdraw.

Talabani, with the backing of Sunni and some secular political parties, notified al-Hakim last week that the opposition coalition members would not join any government led by al-Jaafari.

Al-Hakim tried to fend off the political insurrection by having aides issue statements that alternately sought to placate both the anti-al-Jaafari coalition and his fellow Shiites led by al-Sadr.

Al-Hakim is widely believed to agree that al-Jaafari is a divisive figure but is worried about provoking a split within his own Shiite ranks if he publicly says so.

Al-Jaafari declared Tuesday he would not be "blackmailed" into standing aside.

"Dr. al-Jaafari will not be subdued by blackmail. Dr. al-Jaafari is not violating the constitution. I am not moody, and I am not personalizing the constitution," the prime minister said.

An evening meeting between the Kurdish faction in parliament and the Shiite United Iraqi Alliance failed to break the impasse.

"There is no progress. We are sticking to our stance and they explained their stance," Kurdish legislator Mahmoud Othman told The Associated Press.

The gloves were clearly off as Othman said the Kurds demanded that al-Hakim respond in writing whether he supported al-Jaafari and why.

On Monday, the Shiites blunted Talabani's effort to bring the dispute to a head by calling parliament into session Sunday for the first time since the election and the Feb. 12 certification of the vote — a deadline dictated by the new constitution.

Sensing a split in their ranks and uncertain how to overcome it, the Shiites blocked the convocation of parliament by having the Shiite vice president refuse to sign Talabani's decree. On Tuesday the Shiites sent Talabani a letter formally asking him to delay his decree.