Iraqi Prime Minister Nouri Maliki was dealt a severe blow Monday in his contentious quest for a third term when the country's president and its leading political bloc called on another lawmaker to form a new government.
The move was immediately backed by Washington, which has soured on Maliki.
With Iraq's government deadlocked and the nation confronting a grave threat from Islamic militants, President Fouad Massoum nominated Haider Abadi, the deputy parliament speaker, to be Iraq's next prime minister, the nation's most powerful post
Under Iraqi law, Abadi has 30 days to form a new government, which requires parliament's approval.
The move appeared to be an instance of high-stakes political brinkmanship at a moment when Iraq faces the possibility of disintegration amid a toxic mix of sectarian-fueled political divisions and the rampaging onslaught of an Islamist militia.
The Islamic State, an Al Qaeda breakaway faction, has seized control of vast swaths of northern and western Iraq. Last week, the U.S. military began airstrikes in northern Iraq against Islamic State forces.
A defiant Maliki, who has served in a caretaker capacity since elections in April, went on national television to accuse the president of launching "a coup against the constitution and the political process," and vowing a court challenge.
Forces loyal to Maliki were deployed in the capital and his supporters reportedly took to the streets in what was widely viewed as pushback against the effort to sideline the prime minister.
Maliki has become an extremely polarizing figure in Iraq's brittle governing structure.
Secretary of State John F. Kerry, speaking in Sydney, Australia, warned Maliki against any use of force and voiced the hope that "Mr. Maliki will not stir those waters."
The United States, which has been involved in intense behind-the-scenes talks to find a replacement for Maliki, immediately expressed its "full support" for the new prime minister-designate, the White House said in a statement.
Vice President Joe Biden telephoned the Iraqi president and praised him "for meeting this key milestone," the White House said.
In a separate call with the vice president, the White House said, Iraq's new prime minister-designate "expressed his intent to move expeditiously to form a broad-based, inclusive government."
The apparent break in Iraq's months-long political deadlock puts Maliki, backed by the United States in past years, in an extremely delicate situation.
"If Maliki decides to challenge Abadi while retaining loyalty of his forces, then the situation could spiral in a very uncertain and dangerous direction," Ramzy Mardini, an analyst with the Atlantic Council, a Washington-based think tank, said via email. "At the end of the day, Maliki needs to concede power if a new government is to be formed."
U.S. officials have been working hard behind the scenes to find a replacement for Maliki, regarded by Washington and other critics as a Shiite Muslim hard-liner who has marginalized the Sunni Muslim and Kurdish minorities while putting Shiite loyalists in key posts in the security apparatus and elsewhere.
Support for Maliki has also waned among many Shiite groups, while Shiite Iran — a key Iraq ally — is also reported to have recognized the need to replace Maliki. Detractors charge that Maliki's sectarian agenda has driven many Sunni Muslims to support the Islamic State, despite its throwback agenda for an Islamic "caliphate" and its homicidal policies toward perceived enemies and "infidels."
The Islamic State regards Shiites, who represent a majority in Iraq, as apostates who must be eliminated.
But Maliki's supporters say he is a scapegoat for Iraq's myriad problems, and accuse foreign powers of conspiring to oust him.
Abadi, who spent years in exile in Britain during the rule of former strongman Saddam Hussein, is a member of Maliki's Islamic Dawa Party. He is said to be close to Maliki.
In the Iraqi multi-sectarian political structure, developed after the U.S.-led invasion that ousted Hussein, the prime minister is a Shiite, the president a Kurd and the parliament speaker a Sunni.
The leading Shiite political grouping, the Iraqi National Alliance, backed Abadi for the post, snubbing Maliki.