Growing opposition to Iraq’s Prime Minister Nouri al-Maliki, center, a Shiite who Sunni Arabs and Kurds say has marginalized them, has forced a deadlock over the selection of a new leadership. (Reuters)

Iraq’s parliament has announced that it will convene on Sunday, amid mounting pressure to form a new government that can deal with a litany of challenges that threaten to tear this country apart.

The United Nations had expressed concerns on Monday after parliament cancelled Tuesday’s session to give the country’s deeply divided political factions time to reach an agreement.

Lawmakers had planned to meet on Aug. 12. But the delay would have further imperiled Baghdad’s ability to keep this oil-rich country intact a month after al-Qaeda-inspired militants seized much of Iraq’s north and west, spurring the partial collapse of the nation’s armed forces, politicians and government critics said.

The militants, who call themselves the Islamic State, have declared a caliphate in that territory and have vowed to press on toward Baghdad.

Amid the chaos, Iraq’s Kurdish minority has threatened to hold a referendum on independence for its own largely autonomous region in the north.

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On Tuesday, Iraq’s acting speaker of parliament said that the body would meet Sunday because further delay would “jeopardize Iraq’s security and democracy and will increase the suffering of Iraqis,” the Associated Press reported.

Growing opposition to Prime Minister Nouri al-Maliki, a Shiite who Sunni Arabs and Kurds say has marginalized them in favor of sectarian policies, has forced a deadlock over the selection of a new leadership.

Iraq’s constitution stipulates that the prime minister be a Shiite, the president a Kurd and the speaker of parliament a Sunni.

But because the prime minister is nominated last, Sunni and Kurdish lawmakers, as well as some of Maliki’s Shiite rivals, have said that he must step aside before the two other posts can be determined. Maliki commands the largest bloc in parliament and said over the weekend that he will seek a third term.

The first session of the new parliament, on July 1, ended in a walkout by Sunni Arab and Kurdish lawmakers. Politicians and analysts said the cancellation of the second session was a sign that the process could drag on for months, despite the looming threat of the nation’s total collapse.

“The delay exemplifies what ordinary Iraqis think of their government: weak, dysfunctional, self-serving and, above all, irrelevant,” said Zaineb al-Assam, a senior analyst at IHS Country Risk.

While the politicians bicker, the chances of Baghdad reclaiming the land seized by the Islamic State and its diverse cohort of local allies — all disenfranchised by the Maliki government — is shrinking, analysts say.

However, the formation of a government alone will not present an immediate solution to Iraq’s devastating divisions, according to minority politicians, foreign diplomats and political analysts.

The government will have to restructure the armed forces in a way that empowers Sunnis and work to heal sectarian rifts before it can hope to recapture lost territory, they say.

The threat of sectarian war is also widening. Responding to a call to action by Iraq’s top Shiite cleric last month, Shiite militia fighters have rallied to combat the Sunni militant threat, sparking increasingly sectarian rhetoric and attacks.

A suicide car bombing Monday near a checkpoint in Baghdad’s predominantly Shiite neighborhood of Kadhimiyah killed at least four people, according to local media and residents.

The Islamic State later claimed responsibility for the suicide bombing, as well as one other in the Baghdad district of Washash, via its Twitter account, the SITE Intelligence Group reported.

SITE, which monitors extremist groups, said the bombers targeted a police checkpoint outside Kahdamiya, and a Shiite militia unit on a bridge in Washash.

Earlier in the day, the commander of the Iraqi army’s 6th Division was killed in mortar fire west of Baghdad, near the embattled town of Fallujah, dealing another blow to the crippled force.

Fallujah fell to Sunni militants more than six months ago. Government security forces have been unable to reclaim the city.

A series of mortars also exploded inside Saudi Arabia, near the Iraqi border, on Monday, heightening fears of further spillover from a war that has already spread from Syria into Iraq

Saudi officials said they were investigating the source of the mortar rounds, Reuters reported.

Khalid Ali contributed to this report.