Iraq’s top Shiite cleric called on the nation to rally behind its new prime minister after Nouri al-Maliki stepped down, saying the change of leadership provided an opportunity to halt Iraq’s descent in violence.

Faced with crumbling support among his Shiite allies at home and key partners overseas, including the U.S. and Iran, Maliki announced last night he was giving up his bid for a third term in office. He pledged to support Prime Minister-designate Haidar al-Abadi, who has until mid-September to form a less divisive government better able to battle Sunni Islamists threatening to tear OPEC’s No. 2 producer apart.

Iraqi leaders have to show the “persistent vision capable of saving the country from the dangers of terrorism and division,” Ayatollah Ali al-Sistani said today, according to comments relayed by Ahmed Al-Safi, his representative in the city of Karbala. Maliki was accused by Sunni and Kurdish minorities of leading a sectarian administration, widening rifts that put the nation’s territorial integrity at stake.

During Iraq’s government standoff, Islamic State forces pushed into new areas of northern Iraq, seized towns and oil fields, and sent thousands of members of ethnic Yezidis and Christians fleeing onto the exposed slopes of Mount Sinjar. The chaos loosened Maliki’s grip on power, as past allies blamed him for the stalemate that let the Sunni militants advance.

“All the power is still concentrated with the prime minister,” Mustafa Alani, an analyst at the Geneva-based Gulf Research Center, said by telephone today. “Without reforming the political system, it will only be a temporary solution to the country’s problems. The other ministers — whether Kurdish or Sunni — have no power. This has to change.”

With Iraqi warplanes striking Islamist militant positions in the western city of Fallujah after a series of raids by American fighter jets on the insurgents in the north, Maliki bowed to pressure from his Dawa party to step aside yesterday.

He called on lawmakers to back Iraq’s constitution as they confronted Islamic State, which has captured strategic assets to fund a self-declared Islamic caliphate that stretches across the frontier into Syria. Referring to Abadi by name, he said the decision was “for the higher benefit of the country.”

Iraq’s 2028 bonds gained the most since April after Maliki’s resignation, with yields on the securities dropping 23 basis points, or 0.23 percentage point, to 6.92 percent.

Instability since militants took Mosul, along with its strategic dam, in June and political deadlock in Baghdad has raised concerns that Iraq’s oil output would be disrupted.

West Texas Intermediate for September delivery was at $95.52 a barrel in trading on the New York Mercantile Exchange, down 6 cents, at 4:28 p.m. Sydney time. Brent for October settlement climbed as much as 68 cents to $102.75 a barrel on the London-based ICE Futures Europe exchange.

Abadi’s nomination has had the unusual effect of drawing support both from the U.S. and from Iran, which has major influence over its neighbor Iraq’s Shiites and funds several Shiite militia groups. The EU and the Arab League have also backed Abadi’s appointment.

“Iraq must see a smooth transition of power,” U.K. Foreign Secretary Philip Hammond said in an e-mailed statement. The U.K. hopes that Maliki’s decision to leave office “will contribute to the quick formation of a unified and inclusive government that can address the serious security, humanitarian and political challenges that Iraq faces.”