U.S. leaders hope the government approved by Iraqi lawmakers this week can unite the country's fractured ethnic and religious communities against the extremist group known as Islamic State.
Secretary of State John F. Kerry was quick to applaud the "new and inclusive" government, which he said was a "cornerstone" of the U.S. strategy to defeat the militants whose takeover of large chunks of territory pressured President Obama into a limited bombing campaign in Iraq.
Obama, who plans to explain the strategy in more detail in an address to the nation Wednesday night, called to congratulate the new prime minister, Haider Abadi. He was assured of Abadi's commitment to work with all of Iraq's communities, as well as other countries that have pledged to fight against "this common enemy," the White House said in a statement late Monday.
But the view was far less rosy from Iraq, where the Shiite Muslim Abadi will have a tough time persuading many Sunni Arabs to join the fight against Islamic State and persuading ethnic Kurds to refrain from declaring their own country in the semiautonomous north.
Sunni Muslim leaders have long complained of feeling marginalized by the country's Shiite-dominated leadership and accuse the security forces of committing abuses against members of their minority sect. Those policies, they say, have fueled support for the Sunni-led militants.
Kurds, meanwhile, are locked in power-sharing disputes with Baghdad, including the question of who controls oil revenue from their region and the future of the contested city of Kirkuk, which Kurdish peshmerga fighters seized in June as government forces fled the Islamist onslaught.
While Abadi's supporters describe him as more inclusive and congenial than his predecessor, Nouri Maliki, both leaders hail from the Islamic Dawa Party. The new government lineup includes a number of familiar faces; among them Ibrahim Jafari, a former prime minister, in the role of foreign minister; and former Vice President Adel Abdul Mehdi as the new oil minister.
Maliki was retained in the largely ceremonial role of vice president along with two rivals, Iyad Allawi, another former prime minister, and Osama Nujaifi, the former parliament speaker.
Abadi's Sunni and Kurdish deputies, Saleh Mutlak and Hoshyar Zebari, are also political veterans.
It is a Cabinet "flush with warmed-over ministers from Maliki's government," said Wayne White, a former Iraq analyst for the State Department now with the Middle East Institute in Washington. "It's hardly a signal that a major change in outlook is in the offing."
The political feuding continued until the last minute with Kurdish lawmakers threatening to boycott Monday's vote on the government if their demands were not met. After a long and stormy debate, the Kurdish regional authority gave its approval to Abadi's Cabinet, but only for a provisional period of three months.
"This is not a satisfactory arrangement, since none of the outstanding issues, such as oil and budget, were solved," said Ari Mamshae, a Kurdish analyst based in the northern city of Irbil. "But the leadership has decided to give the situation one more chance so they can be a part of the government and the country."
Iraq now faces "a critical period for how the future of the country will be shaped," he said, "maybe the toughest period for all the communities here, and they all are after their self-interests."
Key positions in the new government, including the defense and interior ministers, were left open, apparently because of disagreement over who should occupy them. Hadi Ameri, who heads the Iranian-backed Badr Corps militia, had been rumored to be in the running for one of the posts, which Abadi said he would fill within a week.
"Apparently calmer heads prevailed (or perhaps there was severe American pressure)," wrote Juan Cole, a University of Michigan historian and prominent commentator on Middle Eastern affairs, in a blog post Tuesday. "That anyone even considered al-Ameri for such a sensitive position is astonishing. During the first Ibrahim Jafari government, the Badr Corps was accused of abuse and the extrajudicial jailings of Sunni Arab rebels."
But even if that thorny problem is resolved, regional experts are skeptical that the new ministerial lineup in Baghdad can win over Sunnis without guarantees from an outside party such as the United States or Iran.
"There has been a certain tendency in the debate to think if we get rid of Maliki, the problem is solved. Or if we get a balance of portfolios, the problem is solved," said Stephen Biddle, a defense expert at the Council on Foreign Relations. "This is a much more sweeping challenge than that."
Some Sunni tribal leaders and former Iraqi military personnel who joined with Islamic State in a bid to overthrow Maliki's government have indicated that they are growing disillusioned with the militants' oppressive tactics.
One of them told the BBC last month that they might be willing to help drive out Islamic State if they thought their rights would be protected by leaders in Baghdad. But the man, identified by a traditional nickname, Abu Muhammad al-Zubaai, said Sunnis felt betrayed by Maliki.
Fighters like al-Zubaai accuse the former Iraqi government of breaking promises made when Sunni tribes joined with U.S. forces against Al Qaeda in Iraq nearly a decade ago. But he was equally dismissive of Abadi and other political leaders in Baghdad.
"We don't want guns from the Americans, we want a real political solution, which the U.S. should impose on those people it installed in the Green Zone," he was quoted as saying about the Iraqi politicians who took over after U.S.-led forces invaded in 2003.
The problem isn't only one of a lack of trust in the civilian government. "The real issue is the Iraqi military," Biddle said.
Islamic State militants have released a stream of videos that illustrate in gory detail what they will do to anyone – Shiite, Kurdish or Sunni -- who stands against them.
"ISIS is going to try to murder the leadership and their families," Biddle said, using a common acronym for the militants. "And if that happens, the U.S. Army isn't going to be on the ground to protect them. It's going to have to be the Iraqi army and police."
Special correspondent Nabih Bulos in Irbil contributed to this report.