BAGHDAD - Iraq's new parliament convened for just under 20 minutes Monday in what was little more than a symbolic inaugural session because of unresolved differences over key government positions - a precarious political limbo three months after inconclusive elections.

The sides are sharply divided over the formation of a government, and analysts and some lawmakers have warned that a decision could still be months away. Prime Minister Nouri al-Maliki is battling to keep his job after the rival Sunni-backed Iraqiya list narrowly won the most seats in the March 7 balloting.

In parliament, Maliki watched as his chief rival, Ayad Allawi, who heads the Iraqiya bloc, and other lawmakers stood to take the oath of office in Arabic and Kurdish. The other half of the session was taken up by the singing of the national anthem and readings from the Quran.

Under Iraq's constitution, the legislature should have chosen a parliament speaker and a president, but these appointments had to be put off because they are part of the negotiations between major political blocs over the rest of the new leadership - including a prime minister and top cabinet officials.

Acting Speaker Fouad Massoum adjourned the session after 20 minutes, saying the parties needed more time to discuss the issue. He said the session would be left open, a technicality aimed at allowing negotiations to continue beyond the 30-day deadline set in the constitution. No date was set for the next meeting.

The session began amid heightened security, a day after insurgents stormed the country's central bank in a coordinated attack that left more than 20 people dead.

Persistent violence has raised fears that al-Qaeda in Iraq and other insurgents are trying to exploit the political deadlock to foment unrest and derail security gains as the U.S. military prepares to withdraw by the end of next year.

Ad Melkert, the U.N. envoy to Iraq, said that it could take from two weeks to three months for the parliament to meet again but that the fact that parliament was seated put pressure on the factions to reach agreement.

"This is an invitation by the newly elected parliament to make sure as soon as possible they can start to function effectively," he said.

Maliki's State of Law coalition, which won 89 seats to come in second place behind Allawi's Iraqiya list, has joined forces with a religiously devout Shiite alliance to form an Iranian-backed bloc called the National Alliance.

Iraqiya leaders have said they should have the first crack at forming the government because they won the most seats. But a March court opinion opened the door to the possibility that the largest bloc could be one created after the election through negotiations - meaning that if the super-Shiite coalition holds together, it could have the right to form the government.

Massoum confirmed the National Alliance as an entity but said it was up to the Federal Court to make a decision on the formation of the government.

The Shiite bloc insisted it should be the one to choose a candidate for prime minister, who would then have to be approved by the president.

Iraqiya lawmakers quickly dug in their heels, saying the coalition would not accept the National Alliance's self-coronation as it had no legal or moral authority do so.

Christopher Hill, the U.S. ambassador to Iraq, said that ultimately, "this will get down to some real hardball politics."

The political jockeying took place amid fears that Sunnis who supported Allawi, a secular Shiite, would turn to violence if they felt disenfranchised.