Top US officials Wednesday upped pressure on key Iraqi leaders as political chaos in Baghdad clouded American hopes for a unity government to tackle the country's sectarian breakdown.
President Barack Obama, meanwhile widened the US effort to convince key regional powers to prevail on Iraqi factions for a political settlement, calling Saudi Arabia's King Abdullah.
Vice President Joe Biden, who frequently burns up the phone lines to Baghdad, talked to the speaker of Iraq's previous parliament, Osama al-Nujaifi, a prominent Sunni leader.
Secretary of State John Kerry meanwhile met a Kurdish delegation in Washington and also spoke to Iraqi Kurdish leader Massud Barzani by phone.
The White House said Biden and Nujaifi agreed on the importance of Iraqis "moving expeditiously to form a new government capable of uniting the country."
Kerry stressed the important role that the Kurds would play in a new multi-sect government in Baghdad, which Washington says is vital to meeting the challenge of Sunni Islamic State (IS) jihadists who have seized vast tracts of Iraqi territory in recent months.
Barzani last week warned that there was no going back on Kurdish rule in the oil-rich northern city of Kirkuk and other towns now defended by Kurdish fighters against Sunni militants.
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He also pledged, in an interview with the BBC, to hold an independence referendum within months, raising the specter of the break-up of Iraq.
State Department spokeswoman Jen Psaki said Kerry emphasized with Barzani the urgency of Kurdish "participation in the government formation process (and) the important role the Kurds (are) playing moving forward."
The first session of Iraq's new parliament, dedicated to choosing a new government, broke up in chaos on Tuesday, with lawmakers walking out and making threats, despite the gravity of the political and security situation.
Many Sunni and Kurdish deputies walked out, causing a quorum to be lost, so a speaker could not be elected, and the session ended in disarray.
Washington has made no secret of the fact that it does not believe Shiite Prime Minister Nuri al-Maliki is the man to lead the new government, blaming him for pursuing sectarian policies in the past -- which the US government believes helped prepare the ground for the IS advance.
But no consensus has emerged on who should succeed Maliki and the prime minister seems determined to cling to power.
Under a de facto agreement, in Iraq, the premier of the government is a Shiite Arab, the speaker Sunni Arab and the president a Kurd.
Obama and Abdullah agreed on the need for separate Iraqi factions to unite to form a politically viable government, the White House said.
"The President thanked the King for Saudi Arabia’s pledge of $500 million dollars to help alleviate the suffering of all Iraqis who have been displaced by the violence," said a White House statement.