The U.N. urged Iraq’s leaders Saturday to overcome their deep divisions and move quickly to form a new government that can unite the country and confront a surging militant threat, warning that failure to do so “risks plunging the country into chaos.”

The Sunni insurgent blitz over the past month has driven Iraq into its deepest crisis since the last American troops left in 2011, pushing bloodshed to levels unseen since the height of the Iraq war, sending Sunni-Shiite tensions soaring and raising the specter of a nation cleaved in three along ethnic and sectarian lines.

Iraq’s new parliament is scheduled on Sunday to hold its second session amid hopes that lawmakers can quickly decide on a new prime minister, president and speaker of parliament — the first steps toward forming a new government. It failed to make any progress in its first session, and postponed its second session until Sunday.

U.N special envoy to Iraq, Nickolay Mladenov, called on lawmakers to attend the meeting and forge an agreement on new leaders. He warned of dire consequences if the current political deadlock drags on.

“It will only serve the interests of those who seek to divide the people of Iraq and destroy their chances for peace and prosperity,” he said in a statement. “Iraq needs a team that can bring people together. Now is not the time for mutual accusations, now is the time for moving forward and compromising in the interest of the Iraqi people.”

In Baghdad, gunmen in four-wheel drive vehicles raided two buildings in a housing complex in the Zayounah neighborhood late Saturday, killing at least 33 people, including 29 women, police said. They say at least 18 people were wounded.

An Interior Ministry official and hospital officials confirmed the casualty figures.

The motive behind the killings was not immediately clear, but police said there are suspicions that the buildings were being used as a brothel.

The officials spoke on condition of anonymity because they were not authorized to brief the media.

Prime Minister Nouri al-Maliki, who has ruled the country since 2006, is under pressure to step aside. His government’s inability to prevent the attack, let alone roll back the militant advance, has sapped public — and international — confidence in his ability to hold Iraq together and lift it out of the crisis.

Al-Maliki’s opponents, and even many of his former allies, accuse him of trying to monopolize power and alienating the Sunni community, and are pushing him to not seek a third consecutive term. Al-Maliki has so far refused to withdraw his candidacy, and points to his State of Law bloc’s capturing the most seats in April elections to claim he has a mandate.

Even though parliament delayed its second session by five days, lawmakers appear unlikely to achieve a major breakthrough Sunday on choosing new leadership, setting the stage for further political wrangling in the days and weeks ahead.

The militants, who have tapped into the deep disaffection among Iraq’s minority Sunnis with al-Maliki, have swept through most of the country’s predominantly Sunni areas in the north and west. The front lines have largely stabilized since their offensive encountered greater resistance in majority Shiite areas, although heavy fighting rages on.

On Saturday, Iraqi troops supported by Shiite militiamen battled Sunni militants who had seized at least partial control of a military base outside the town of Muqdadiyah, about 90 kilometers (60 miles) north of Baghdad. The troops and pro-government fighters succeeded in pushing insurgents out of the nearby hamlet of Nofal, but the base remained split between the warring sides, police officials said.

Police and hospital officials said the bodies of 16 pro-government fighters — a mix of soldiers and militiamen — killed in the fighting were taken to the morgue in Muqdadiyah, and another 15 were taken to the provincial capital of Baqouba. They said a family of five, including three children, was killed in government airstrikes on Nofal.

The officials spoke on condition of anonymity because they were not authorized to brief the media.

To the west of Baghdad, the government airlifted some 4,000 volunteers to Ramadi to boost their forces trying to defend the city from militant attack, said Gen. Rasheed Flayeh, the commander of operations in Anbar province. The operation began Friday and finished Saturday.

Ramadi is the capital of Anbar, an overwhelmingly Sunni province and one of the most active battle fronts in Iraq. The Islamic State extremist group and other Sunni militants seized control of the Anbar city of Fallujah and parts of Ramadi in January. The government has since reasserted its control of Ramadi, but Fallujah remains in insurgent hands.

The vast majority of volunteer fighters are Shiites who have answered a call from the country’s top Shiite cleric, Ayatollah Ali al-Sistani, to defend Iraq from the Sunni militants led by the Islamic State group, which has unilaterally declared the establishment of an Islamic state ruled by Shariah law in the territory it controls straddling the Iraq-Syria border.

The government’s reliance on Shiite militias — who have deployed in sizeable numbers to several cities across the country — to help counter the militant threat has ramped up sectarian tensions, fueling fears that Iraq could return to the wholesale sectarian bloodletting that engulfed the country in 2006 and 2007.

(AP)