By Raheem Salman, Oliver Holmes and Ned Parker
BAGHDAD (Reuters) - It is no coincidence that Iraq's new prime minister is more likeable than his predecessor. Haidar al-Abadi was handpicked last month to detoxify a political system poisoned to the point of collapse under the dour and mercurial Nuri al-Maliki.
A former engineer widely described as an amiable and witty pragmatist, Abadi is expected to vindicate supporters at home and abroad this week by wooing Sunnis, Kurds and members of his own divided Shi'ite majority to form a unity government.
Diplomats and politicians from across Iraq's political spectrum say they believe Abadi is far better suited to bridging differences than Maliki, who was pushed out of office last month with a third of his country in the hands of Islamic State.
But behind the scenes, many say it will take more than a change in personality at the top to save Iraq from collapse.
A senior Kurdish politician listed the tasks, which include winning Sunnis back from armed revolt, persuading Kurds not to break away and convincing Abadi's own Shi'ites that he has the steel to protect them from fighters bent on their annihilation.
"He has to make Maliki happy. He has to make the (Shi'ite religious leadership) happy. He has to make the Sunnis happy to turn them against IS. He has to make us very, very happy. He has to make the Americans happy, he has to make the Iranians happy."
"Can he? I don't think so."
HONEYMOON IS OVER
The new leader takes office with the public good will of nearly all of Iraq's major political groups, as well as the two most influential outside powers, Iran and the United States, who both pulled the plug on Maliki as the army collapsed in the face of an onslaught by Islamic State militants.
Before Abadi was picked as leader, a former U.S. diplomat who worked in Baghdad identified him as someone with the right temperament: less conspiratorial and guarded than Maliki and less inclined to take disagreement personally.
The diplomat described watching Abadi tell a joke at the start of a meeting, disarming a tense atmosphere in a way that would have been impossible for Maliki.
Mowaffak al-Rubaie, a former Iraqi national security advisor and leading Shi'ite politician, said Abadi was already off to a good start by ensuring that political groups inside Iraq, as well as Washington and Tehran, have given him their backing.
But the prime minister designate, who has yet to be sworn in to office, has already hit obstacles, with politicians using brinkmanship to pressure him, said another Western diplomat.
"The honeymoon is officially over."
In his own public remarks, Abadi, a religious Shi'ite who spent two decades in exile in Britain during the rule of Sunni dictator Saddam Hussein, has emphasized the importance of reconciliation among Iraq's sects and ethnic groups.
In an interview with Reuters in June when Islamic State had just begun its lightning advance through northern Iraq, he stressed a need for the government in Baghdad to woo back Sunnis who had reluctantly embraced the fighters.
"These alliances between (IS) and others have a strategic fault line that is starting to crack," he said.
While Maliki is known for emphasizing the importance of consolidating power, Abadi spoke of decentralizations: "There is a huge central authority that is unnecessary," he told Reuters.
Despite having had two brothers executed under Saddam, he acknowledged a need to reform a law banning members of former dictator's Baath Party from state positions and the military.
"The law in implementation was far from just.”
He called for "wide-ranging amnesties", a key demand of the Sunni community for the thousands from their sect jailed for years on blanket terrorism charges, first by the Americans and then the Iraqi security forces.
"Everyone agrees now we need to do something about this - short of (freeing) criminals."
Yet despite his conciliatory manner, politicians from rival groups say Abadi has never veered from the party line of his own Shi'ite Islamist faction, the Dawa Party, until now firmly led by Maliki.
In 2010, when there was a dispute over the formation of the government, Abadi participated in a press conference accusing Maliki's secular opponents of terrorism.
FIRST CLASS CITIZENSHIP FOR SUNNIS
The most urgent task for the government is tackling the insurgency by Islamic State. Maliki's opponents, both inside Iraq and abroad, accused the outgoing leader of making the problem worse by excluding Sunnis from the political process, alienating them to the point that they embraced the fighters.
Sheikh Mohammed Saleh al-Bashari, a 52-year old leader of Sunni anti-government demonstrations Maliki tried to crush last year, said Abadi must distance himself from his predecessor.
“Abadi should let the Sunnis feel that they are first class citizens, not like Maliki, who made them feel that they are not part of this country."
He said Abadi will fail to woo the Sunnis unless he can disband the Shi'ite militias that Maliki first opposed but in the past year increasingly relied on to defend Iraqi cities when the army proved incapable.
"Maliki was stronger than him and he couldn’t do it," Bashari said, adding that Sunnis would never fight against Islamic State as long as they see the Sunni Islamist fighters as protectors against the Shi'ite militias.
"The tribes will never fight any group which defended their cities, including the Islamic State. Without them, we would be slaughtered by the militias which the government brought to Anbar, Salahuddin and Diyala" provinces.
While Maliki's relations with Sunnis proved catastrophic, his dealings with Iraq's other big minority, the Kurds, were little better, with officials in the Kurdish region increasingly discussing the possibility of seeking independence.
The senior Kurdish politician, who asked not to be identified to allow him to speak freely about Abadi, said the change in personalities from Maliki was welcome, but would not be enough by itself to win over Kurds. Disputes with Maliki were political in nature, not a factor of his personality, he said.
"Our problems with Maliki were not personal. So how is Haider al-Abadi going to form an inclusive power-sharing government and guarantee he's not going to commit the same mistakes Maliki was committing in the last ten years?"
He described Abadi, longtime head of parliament's financial committee as "one of the hawks within the Dawa party" in Baghdad's dispute with the Kurds over their share of Iraq's oil revenues, which led to Baghdad halting such payments in January.
The Kurds would demand from Abadi their rightful share of the budget, a referendum over control of disputed territories and a law, in limbo for seven years, defining the rights of national, regional and local governments over oil resources.
"He has to do the opposite of what Maliki did. Whatever Maliki did, if he can do the opposite," the politician said.
DISCORD AMONG SHI'ITES
Demands on Abadi will come not just from the minority Sunnis and Kurds, but from his own fellow Shi'ites, whose fractiousness was put on full display when Maliki refused for days to accept the Dawa Party's decision to replace him.
Hajem Hassani, former parliament speaker and a Sunni from the small Turkmen ethnic minority, described Abadi as a good friend but said the new premier would first have to sort out problems in his own party.
"He has a hard task in front of him because it isn’t like he is going to have all the power to handle the situation. He is going to have a hard time," he said. "I hope he will have the full support of his party. When you don't have that full support, you'll have some tough times with your own group, let alone with the others."
Amir al-Kinani, a lawmaker from the Sadr movement, one of Dawa's biggest Shi'ite rivals, said Abadi needs to stand firm against party patronage and cronyism that has destroyed popular faith in the government.
"He should be monitoring his ministers. If there is a minister who is suspected of corruption, the person should not continue in his position," he said.
In his interview with Reuters in June, Abadi himself described the rot in Iraq's governing institutions as going far deeper than the disputes among political leaders at the top.
“Unfortunately, we would agree on the strategy but not the details, and then we leave the procedures to committees. Those higher up don't participate, and then it stalls. We move on to another issue and we forget about it. And six months later we see nothing has been done," he said in June.
"And everyone blames the other."
(Additional reporting by Isabel Coles in Arbil; Editing by Peter Graff)