Iraq's new prime minister-designate won swift endorsements from both the United States and Iran on Tuesday as he called on political leaders to end crippling feuds that have let jihadists seize a third of the country.
Haider al-Abadi still faces a threat closer to home, where his Shi'ite party colleague Nuri al-Maliki has refused to step aside after eight years as premier that have alienated Iraq's once dominant Sunni minority and irked Washington and Tehran.
However, a senior government official said commanders of military forces that Maliki deployed around Baghdad on Monday had pledged loyalty to President Fouad Masoum and to respect the head of state's decision to ask Abadi to form a new government.
As Western powers and international aid agencies considered further help for tens of thousands of people driven from their homes and under threat from the Sunni militants of the Islamic State near the Syrian border, Secretary of State John Kerry said the United States would consider requests for military and other assistance once Abadi forms a government to unite the country.
Underscoring the convergence of interest in Iraq that marks the normally hostile relationship between Washington and Iran, the head of Tehran's National Security Council congratulated Abadi on his nomination. Like Western powers, Iran has been alarmed by the rise of Sunni militants across Syria and Iraq.
Abadi himself, long exiled in Britain, is seen as far less polarising, sectarian figure than Maliki, who is also from the Shi'ite Islamic Dawa party. Abadi appears to have the blessing of Iraq's powerful Shi'ite clergy.
Iraqi state television said Abadi "called on all political powers who believe in the constitution and democracy to unite efforts and close ranks to respond to Iraq's great challenges".
One politician close to Abadi told Reuters that the prime minister-designate had begun contacting leaders of major groups to sound them out on forming a new cabinet. The president said on Monday he hoped he would succeed within the next month.
Maliki angrily dismissed Abadi's nomination on Monday as illegal. But there was no further sign of opposition on Tuesday.
While US officials have been at pains not to appear to be imposing a new leadership on Iraq, three years after US troops left the country, President Barack Obama was quick to welcome the appointment. Wrangling over a new government since Iraqis elected a new parliament in April has been exploited by the Islamic State to seize much of the north and west.
Obama has sent hundreds of US military advisers and last week launched air strikes on the militants after they made dramatic gains against the Peshmerga forces of Iraq's autonomous ethnic Kurdish region, an ally of the Baghdad authorities.
US officials have said the Kurds are also receiving direct military aid and US and British aircraft have dropped food and other supplies to terrified civilians, including from the Yazidi religious minority, who have taken refuge in remote mountains.
Kerry, who on Monday had warned Maliki not to resort to force to hold on to power, said on Tuesday that Abadi could win more US military and economic assistance.
"We are prepared to consider additional political, economic and security options as Iraq's government starts to build a new government," he told a news conference in Australia, where he also reaffirmed that Washington would not send combat troops.
"The best thing for stability in Iraq is for an inclusive government to bring the disaffected parties to the table and work with them in order to make sure there is the kind of sharing of power and decision-making that people feel confident the government represents all of their interests," Kerry added.
It remains unclear how much support Maliki, who remains acting premier, has to obstruct the formation of a new administration. One senior government official told Reuters that his fears of a military standoff in the capital had eased:
"Yesterday Baghdad was very tense," he said. "But key military commanders have since contacted the president and said they would support him and not Maliki."