Shiite clerics called on Iraqi civilians to take up arms against advancing Sunni insurgents inspired by al-Qaeda, drawing the battle lines for a major sectarian confrontation in the fracturing state.

Shiite clerics called on Iraqi civilians to take up arms against advancing Sunni insurgents inspired by al-Qaeda, drawing the battle lines for a major sectarian confrontation in the fracturing state.

Shiite clerics called on Iraqi civilians to take up arms against advancing Sunni insurgents inspired by al-Qaeda, drawing the battle lines for a major sectarian confrontation in the fracturing state.

Prime Minister Nouri al-Maliki will not readily surrender power and is unlikely to do so unless chief ally Iran insists that he go, Maliki’s foes and supporters are warning as pressure mounts on the embattled Iraqi leader to make concessions to rivals or step aside.

The pressure intensified Friday with an appeal by Iraq’s most revered Shiite cleric for the swift formation of a new government capable of uniting Iraqis against the threat posed by Sunni militants who have seized large chunks of Iraqi territory in the past 10 days.

Grand Ayatollah Ali Sistani did not directly mention Maliki, but he called for the creation of a government that has “broad national support,” a clear reference to Maliki’s failure to win the confidence of the country’s Sunnis during his eight years in office. The message was delivered by his representative Ahmed al-Safi in the holy city of Karbala.

Sistani’s message echoed one delivered by President Obama on Thursday that hinted at a withdrawal of U.S. support for Maliki, whose authoritarian style and discriminatory behavior toward Iraq’s Sunni minority are widely blamed for the bloodshed threatening to tear the country apart.

“Only leaders that can govern with an inclusive agenda are going to be able to truly bring the Iraqi people together and help them through this crisis,” Obama said while announcing the dispatch of as many as 300 U.S. troops to assist Maliki’s forces in their battle against Islamic State of Iraq and Syria (ISIS) extremists.

Persuading Maliki to step down could be difficult, say his political foes, who have long sought to persuade the United States that Maliki is a liability but have repeatedly failed to form a viable coalition against him.

“This is not going to be easy,” said Deputy Prime Minister Saleh al-Mutlak, a Sunni who has led many fruitless efforts to build parliamentary coalitions against Maliki in the past. “Maliki will not go quietly.”

Previous attempts to oust Maliki through constitutional means have foundered on the inability of his foes to unite around an alternative candidate. According to the parliamentary system of government spelled out in Iraq’s constitution, drawn up under U.S. supervision in 2005, whoever commands a majority of seats in the parliament forms the government, making it theoretically possible to replace any leader by mustering the support of enough lawmakers.

A bigger obstacle to forcing Maliki’s departure, however, could be the support of Iran, which has shown no sign that it is preparing to dilute its backing for the prime minister. The support includes funding and training for the private militias that back Maliki, many of whose members have taken to the streets in recent days in response to a call to arms.

“The only outside power that could get rid of Maliki is Iran,” said Kenneth Pollack of the Brookings Institution in Washington. “And even if the Iranians decided they wanted him out, I am not sure they could do it. Maliki has the loyalties of the security forces and the loyalty of the militias, and it is going to be extremely hard to get rid of him.”

The question of replacing Maliki is timely because his second four-year term has expired. Elections in April produced a new parliament, and the constitution says a new government must be formed with the support of a majority of the 328 new lawmakers.

The question is one of growing urgency because there is a constitutional vacuum in the country. Within days of ISIS’s seizure of the northern city of Mosul, the current parliament’s mandate expired. Until the new one meets, Maliki is effectively governing unchecked by any law or oversight, and that is raising concerns about a continued concentration of power in his hands.

In one example of how he could use the vacuum to increase his hold on power, on Thursday he announced salaries for the mostly Shiite volunteers who have flocked to join militias in recent days.

Sistani, a moderate who is regarded as the world’s most influential Shiite figure, expressed remorse in his Friday address for an earlier call to confront the ISIS militants that inspired a rush to arms by Shiites. The appeal “was not only about one sect,” he said, and was intended to persuade Iraqis to join the official security forces, “not to form militias outside the law.”

Reflecting concerns that the constitution could lapse if its provisions aren’t observed, it is also “very important,” Sistani said, for the new parliament to observe the time limits spelled out in the constitution for its first meeting — which should occur within the next month.

A variety of candidates are being touted as potential successors to Maliki, including Adel Abdul Mahdi, a Shiite former vice president from the Islamic Supreme Council of Iraq party; former prime minister Ayad Allawi, whose secular bloc has the support of mostly urban, secular Sunnis; Ahmed Chalabi, whose name often surfaces as a possible compromise candidate at times of crisis; and Jaafar al-Sadr, a cousin of prominent Shiite cleric Moqtada al-Sadr who has little political experience and no constituency.

Another option floated is for a candidate from Maliki’s own Dawa Party to replace him. Names often mentioned include Tariq Najm, an adviser to Maliki who is thought to be closer than the prime minister to Iran; Khudair Khuzaie, who is a vice president but is regarded as lacking in clout; and Ali Adeeb, a senior party member who is regarded as even more sectarian and uncompromising when it comes to dealing with Iraq’s Sunnis than Maliki.

But the result of the recent election, which gave Maliki a bigger share of the vote than in the previous parliament, won’t make it easy for rivals to replace him.

Maliki won by far the largest number of seats, 92. His nearest rival, the bloc led by Moqtada al-Sadr, won 34. Several other Shiite, Sunni and Kurdish coalitions won 10 seats or more, giving them a total of about 164 seats, one less than the 165 required for a majority.

Correction: Previous versions of this story and an earlier correction inadequately characterized Maliki’s remarks about payment for Iraqis who volunteer to fight ISIS. Maliki announced salaries Thursday for the mostly Shiite volunteers who have joined militias in recent days in response to a call from Sistani.