US Vice President Joe Biden spoke by telephone on Sunday with Iraqi Prime Minister Nuri al-Maliki about violence in Baghdad and a political crisis that has erupted in the week since the last American troops left Iraq.
US officials, diplomats and Iraqi politicians have been in a flurry of talks to calm a crisis that threatens to push Iraq back in the kind of sectarian strife that took the OPEC oil producer to the edge of civil war only a few years ago.
Just a week after the last US troops left, the upheaval risks scuppering an uneasy power-sharing government that splits posts among the Shia National Alliance coalition, the mostly Sunni-backed Iraqiya bloc and Kurdish political movement.
Iraqi lawmakers and politicians tried on Sunday to negotiate an end to the turmoil days after Maliki, who is a Shia, sought his Sunni vice president's arrest on charges he ran an assassination squad, and tried to fire his own Sunni deputy.
Biden, who also spoke to Iraqi Kurdistan Regional Government President Massoud Barzani, has played a diplomatic role during the US military's departure, travelling to Iraq and discussing the signs of rising sectarian tension with Iraqi leaders.
"The Vice President offered condolences on the recent violence in Baghdad, exchanged views with both leaders on the current political climate in Iraq and reiterated our support for ongoing efforts to convene a dialogue among Iraqi political leaders," the White House said in a statement.
A string of bombings across Baghdad, including a suicide attack on a government building, killed 72 and wounded 200 on Thursday, underscoring Iraq's still vulnerable security situation as the political crisis gripped the country.
Tuesday could be a key test for how Iraq's turmoil develops when the cabinet is scheduled to meet and Iraqiya government ministers will decide whether to attend or boycott the meeting. Iraqiya lawmakers have already temporarily suspended their participation in parliament, which is in recess.
"There was a delegation from the National Alliance that met Iraqiya last night," said Haider al-Abadi, a senior Shia lawmaker and Maliki ally.
"If Iraqiya wants to participate in real talks, it has to go back to parliament and the government because a parliament boycott is not acceptable," he added.
Nearly nine years after the invasion that toppled Saddam Hussein, sectarian tensions still run close to the surface in Iraq, where sustained violence between Sunni and Shia communities killed thousands of people in 2006-07.
Maliki last week sought the arrest of Sunni Vice-President Tareq al-Hashemi, a key member of Iraqiya, on charges he ordered his bodyguards to carry out assassinations and bombings.
The prime minister also asked parliament to fire his Sunni deputy, Saleh al-Mutlaq, another Iraqiya leader, after he branded Maliki a dictator.
Hashemi, who denies the charges and says he is victim of a political vendetta, is now in Iraqi Kurdistan, where he is unlikely to face immediate arrest. He has asked for his case to be transferred there. Semi-autonomous Kurdistan has its own government and armed forces.
"The political dimension of this is to get rid of all those who oppose Nuri al-Maliki, it is clear," Hashemi told Reuters in a weekend interview.
Shia political leaders say the Hashemi case is a criminal issue now with the courts and is not politically motivated. But Maliki's moves are fanning minority Sunni fears that they are being marginalised. Since Saddam's fall, Iraq's Shia majority has risen and Sunnis say they feel they have been pushed out of decision-making.