Four months after the national elections, Iraqi leaders have failed to form the country's first permanent post-Saddam Hussein parliament due to bickering over the prime minister's post and other ministerial berths.

The plan to convene the assembly, which was elected in December, was announced as the United States and the United Nations redoubled efforts to urge Iraqi leaders to agree on a government to help quell raging violence.

However, a key sticking point in negotiations appeared no closer to a solution as embattled Prime Minister Ibrahim Jaafari hardened his determination to remain in office.

"I am the candidate and the alliance chose me," Jaafari told reporters, referring to the United Iraqi Alliance (UIA) which won 128 out of 275 parliament seats in the December election and chose Jaafari by a single vote in February.

"It has been announced that I am the candidate and that is enough."

Iraq's Kurdish and Sunni leaders have opposed Jaafari's candidacy, saying he has been unable to curb the sectarian violence that has ravaged the country since the bombing of a major Shiite shrine in Samarra in February.

With the Shiite alliance failing to come up with a solution to the Jaafari issue, the Sunni bloc warned that it would take the matter into its hands.

"In the next two days if the alliance fails to come up with a solution, there would be no choice but to all other parliamentary blocs to join hands and form a government," said Zhafer al-Ani, spokesman of Sunni-led National Concord Front which has 44 seats in the assembly.

The non-Shiite blocs hold 145 seats in the 275-member parliament, more than the number required to form a government. The Iraqi constitution stipulates that the party forming the government must have a simple majority in the parliament.

Kurdish lawmaker Mahmoud Othman said that leaders were zeroing in on candidates for other parliamentary posts.

Othman said Jalal Talabani is the choice as president, Shiite leader Adel Abdel Mahdi as vice president, Sunni leader Tareq al-Hashemi as the other vice president, Sunni politician Adnan al-Dulaimi as the parliament speaker, Shiite sheikh Khalid al-Attiya as the deputy speaker and Kurdish lawmaker Aref Tayfur as the second deputy speaker.

The first permanent post-Saddam Hussein parliament was inaugurated on March 16 but swiftly adjourned amid little sign of a deal on a government of national unity.

An earlier parliament session, scheduled for April 17, was cancelled.

US President George W. Bush on Wednesday renewed calls for the formation of a national unity government while the UN special envoy to Iraq held talks with Shiite clerics in an attempt to break the impasse.

"We fully recognize that the Iraqis must step up and form a unity government. Vacuums in the political process create opportunity for malfeasance and harm," Bush said.