(CNN) -- There may not be many issues on which the Islamic Republic of Iran and the White House agree, but dumping Iraqi Prime Minister Nuri al-Maliki in favor of Haider al-Abadi is one of them. The message from a growing number of actors inside and outside Iraq is the same: Maliki must go if the country is to be saved.
Iraq's unofficial power-sharing agreement dictates that the President is a Kurd, the Speaker of Parliament a Sunni and the Prime Minister a Shia. This division of power among Iraq's three main groups has helped to prevent Maliki's growing authoritarianism during his eight years as premier.
In 2011, a Sunni Vice-President -- Tariq al-Hashimi -- fled to Kurdish northern Iraq after Maliki ordered his arrest and accused him of terrorism. The Prime Minister also suppressed Sunni protests in western Iraq, giving the Islamic State in Iraq and Syria (ISIS) the opening it needed in courting Sunni tribes.
Now the much-maligned constitution may have come to the rescue. It stipulates that the President -- currently Fuad Masum, who was elected on July 24th -- should call on the leader of the largest bloc in parliament to form a new government within 30 days. Maliki said that was him as leader of the State of Law bloc, but Maoum was open to other interpretations. Shia politicians in the broader but loose National Alliance wrote to the President Monday to say they could muster more votes than Maliki.
It was -- in essence -- a coup within the Prime Minister's own party.
So, can a new government be formed?
Coalition-building in Iraq since the overthrow of Saddam Hussein has never been easy, but Nuri al-Maliki has arguably made it harder through his growing reliance on a Shia bloc loyal to him. He has built up special forces outside the regular army and accentuated sectarianism in Iraqi politics. In the process, he has alienated the Kurdish and Sunni minorities.
After April's elections, there was a sense of paralysis. It took several attempts just to get a quorum in the new parliament so a new President could be appointed. Maliki stayed on as Prime Minister, believing opposition to him would crumble because no other viable candidate would emerge.
The rapid advance by ISIS and the growing disenchantment of the Shia establishment with Maliki's obstinate refusal to give way broke the logjam. Two events in the last few days seem to have turned doubters into opponents.
The first was ISIS' capture of the strategically vital Mosul dam, just as the fighters also put pressure on Kurdish towns to the north. The dam is a critical link in central Iraq's power and water supplies -- but its destruction would flood a huge tract of the country.
The second (and possibly related) event was the strongest suggestion yet from Grand Ayatollah Ali Al-Sistani -- the undisputed leader of Iraq's Shia -- that Maliki's time was up. Through a representative at Friday prayers last week, Sistani warned that politicians who put their self-interest before the national interest were committing a "grave mistake."
Sistani's position created fissures within the State of Law coalition and Maliki's own Dawa Party, according to Ayham Kamel of the Eurasia Group political consultancy firm, "and provided members of the State of Law coalition with political cover to defect to the National Alliance."
Who is Haider al-Abadi?
Haider al-Abadi was born in Baghdad in 1952. A long-time member of the Dawa Party (he is said to have joined as a teenager) he was one of thousands of prominent Iraqis -- especially Shia -- who left the country during Saddam Hussein's rule. Al-Abadi left to study abroad after receiving a bachelor's degree in 1975, and stayed away as Hussein tightened his grip on the country. Two of his brothers were not so lucky; they were executed in 1982 for belonging to the Dawa Party. The following year, the regime cancelled Haider's passport.
Al-Abadi spent many years in Britain, where he received a doctorate in electrical engineering at the University of Manchester. His father, who had been a prominent Iraqi official, was accused of insufficient loyalty to the regime and was forced to retire in 1979. He moved to Britain and lived there until his death.
After Hussein was ousted, al-Abadi returned to Iraq in 2003 and became Communications Minister in the interim government, where his language skills and international contacts proved valuable. According to his biography, al-Abadi was put in charge of ridding the northern Iraqi city of Tal Afar of al Qaeda in 2005, and successfully brought tribes together in doing so. It may prove to have been useful experience; Tal Afar is now under the control of ISIS.
In interviews in recent weeks he has stressed the need for unity and compromise in the face of a common enemy, saying all groups had been weakened in the face of the militant threat. He has argued fervently against the division of Iraq and said he is open to help from Iran (where many Dawa Party members lived in exile.)
What happens to Maliki?
Despite the growing odds against him, Nuri al-Maliki is not going quietly. He has deployed militia loyal to him around and inside the Green Zone -- the center of federal power in Iraq -- and says he will challenge the President's move in court over a "grave constitutional breach."
"Maliki will pressure the constitutional court to issue a clearer ruling that prevents Abadi from assuming power," says Kamel of the Eurasia Group.
Maliki also remains head of the armed forces and intelligence services, and commands the Defense and Interior ministries. Kamel suggests "Maliki could also approve a new military offensive against ISIS and claim that a leadership change would jeopardize the security environment."
But the army has made it clear that its loyalty is to the state, not the Commander-in-Chief. Senior commanders have been alienated by Maliki's formation of militia and special brigades that have taken resources and power from the military, as well as political patronage in senior appointments. Loyalty was prized above ability.
There is the danger that die-hard loyalists to Maliki could put up a fight, drawing the security forces into a battle for control of Baghdad just as they face ISIS not far from the capital. U.S. Secretary of State John Kerry alluded to this risk Monday, saying: "The government formation process is critical in terms of sustaining stability and calm in Iraq and our hope is that Mr. Maliki will not stir those waters."
The Institute for the Study of War notes that the powerful Iranian-backed Shia militia, Asa'ib Ahl al-Haq, has already abandoned Maliki. And it adds that "Iranian-directed militia activities will likely neutralize other elements of the ISF (Iraqi Security Forces) that are loyal to Maliki." Even so, groups like the Badr Brigades -- if they decide to support Maliki -- have the potential to stir trouble.
Some observers suggest Maliki be given a ceremonial position -- perhaps a Vice-Presidency -- to provide him with a dignified exit. But for now he appears to have been outmaneuvered by the same tactics he used so effectively in the past. As Joel Wing writes in his Musings on Iraq blog, "Rather than finding the chinks in his opponents' armor like he did in 2010, it was [his own] State of Law who ended up breaking apart. Now he's left to verbal threats, claims of illegality, and intimidating maneuvers."
"With all the support Abadi is garnering, it will all be over when he presents his ruling coalition for approval to parliament in the next 30 days," writes Wing.
What do the Kurds and Sunnis think?
So far much of the political drama has played out among the Shia parties in Baghdad. Sunni and Kurdish groups are preoccupied with more pressing problems in the face of the ISIS threat, and are waiting to see how al-Abadi follows through on his conciliatory language.
The Dawa Party's Shia Islamist complexion may make Sunnis and Kurds wary of al-Abadi. After all, until recent weeks he was a close aide of Maliki, and therefore -- in the eyes of many Sunnis and Kurds -- guilty by association with an increasingly sectarian Shia program.
The Dawa Party also favors a strong central government, and the Kurds may be concerned that their gains amid the chaos of the last few months -- especially in taking control of Kirkuk and its oil fields -- will be challenged.
Their veteran leader, Massoud Barzani, has said that recent events have forever changed the nature of Iraq -- and suggested a referendum on Kurdish independence may be held.
U.S. Vice President Joe Biden urged Barzani "to work closely with Dr. Abadi as he works to build a diverse, inclusive government," according to a statement from the White House. But the Kurds will want to see concessions on what they would regard as a fairer division of Iraqi oil revenues, as well as more generous supplies of weaponry from Baghdad with which to fight ISIS.
There is also the issue of the Kurds' unilateral sale of oil, which has been vociferously opposed by the government in Baghdad.
What's the view of the international community?
There is rare unanimity that al-Abadi, while not exactly a consensus figure, has to be given a chance to "reach across the aisle" in the face of the existential threat posed by ISIS, which now controls swathes of north and western Iraq.
Obama has already reached out to al-Abadi to urge him to form a cabinet representative of Iraq's ethnic and religious communities. And al-Abadi has made the right noises in response. The White House said he had "expressed his intent to move expeditiously to form a broad-based, inclusive government" in a phone call with the President.
The language out of Tehran has been more restrained, but equally pointed. Ali Shamkhani, a member of Iran's Supreme National Security Council, said on Tuesday his country backed the legal procedure taken in the nomination of the Prime Minister. Saudi Arabia -- which has long loathed Maliki -- also joined the chorus, congratulating President Masum on nominating al-Abadi.
The question is whether, if and when Maliki is forced from office, the Obama administration will step up its participation in the campaign against ISIS. John Kerry has already (not surprisingly) ruled out ground troops. But he said Tuesday: "What we are really looking for is a way to support Iraq, support their forces whether it's training, equipment of one sort or another that can help them stand on their own two feet."
To Max Boot at the Council on Foreign Relations, the question is: "Will we stick to a minimalist containment strategy designed to prevent ISIS from taking Erbil and murdering the Yazidis? Or will we implement a much more ambitious strategy to enable the defeat of ISIS?"
If the latter, the U.S. may need to get the new government's assent for arming Kurdish Peshmerga forces directly, so ISIS can be challenged on two fronts.
U.S. airstrikes appear to have stemmed ISIS' momentum in the Sinjar area near the Syrian border and east of Mosul for now, and better coordination between the Iraqi army and Kurdish forces will further pressurize ISIS. But the militants are resilient, well-organized and have seized weaponry such as armored personnel carriers and tanks from Iraqi armories.
Success on the battlefield -- long awaited but so far unrealized -- may be al-Abadi's best ally as he tries to stitch together a majority in parliament.