Baghdad and Erbil, Asharq Al-Awsat—The Custodian of the Two Holy Mosques, King Abdullah Bin Abdulaziz, congratulated Iraq’s new leaders, President Fuad Masoum, Prime Minister-designate Haider Al-Abadi and Speaker of Parliament Salim Al-Jabouri, on Tuesday.

In his messages, King Abdullah expressed his wishes for lasting security, stability and prosperity in Iraq, and for unity to be restored to the Iraqi territory and its people.

The message from the Saudi monarch comes amid growing domestic and international backing for Abadi and the increasing isolation of incumbent caretaker Prime Minister Nuri Al-Maliki, who nevertheless continues to dispute his rival’s appointment.

Ibrahim Bahr Al-Uloum, MP for the Shi’ite-led Islamic Supreme Council of Iraq (ISCI) and former oil minister, told Asharq Al-Awsat: “Abadi is an acceptable figure who is a politician and a technocrat, in addition to being moderate. He favors openness to the national arena which is very important at these times, which means this change will provide a window of hope to take Iraq out of its crisis.”

Raed Fahmi, a member of the political bureau of the Iraqi Communist Party and former science and technology minister, told Asharq Al-Awsat that “the political content of the change is important and must be supported by all nationalist forces, because Maliki turned into an obstacle and failed to cooperate seriously with others.”

The appointment of Abadi received widespread support in Iraq, as well as neighboring countries, including Saudi Arabia, Iran and Turkey. Westerns states, including the US, also welcomed Abadi’s appointment, with President Barack Obama calling his appointment earlier this week “a key milestone.”

Obama, who spoke to Abadi by phone and urged him to speed up the formation of the government, said: “This new Iraqi leadership faces a difficult task . . . it must restore public trust in it and take steps which show its determination.”

Tehran, formerly a key ally of Maliki, also appears to have dropped its backing for the embattled premier and thrown its weight behind Abadi.

In a statement published on his website on Wednesday, Iran’s Supreme Leader Ayatollah Ali Khamenei said: “I hope the designation of the new prime minister in Iraq will untie the knot and lead to the establishment of a new government and teach a good lesson to those who aim for sedition in Iraq.”

US Secretary of State John Kerry, meanwhile, urged Abadi to form a unity government soon. Speaking during a visit to Sydney, Kerry said: “We urge him [Abadi] to form a new government as soon as possible; the United States is prepared to support a new Iraqi government which includes all parties, especially in their fight against the Islamic State of Iraq and Syria (ISIS).”

Meanwhile, Abadi has kept the door open to Maliki, a fellow member of the Islamic Da’wa Party, to remain involved in politics, calling him “a brother and a comrade” and praising his “enormous achievements.”

Despite the widespread support for Abadi, Maliki has continued to insist on mounting a legal challenge to President Masoum’s appointment of Abadi.

In a televised address on Wednesday, Maliki said his rival’s appointment was unconstitutional and had “no value” without a Federal Court ruling, on the grounds that Iraq’s constitution calls for the head of the largest bloc in parliament to be given the first chance to form a government.

“This government is continuing, and will not be changed except after the Federal Court issues its decision,” he added.

Maliki’s State of Law coalition won the largest number of seats in Iraq’s parliamentary election in May, but fell short of an overall majority.

Iraqi legal expert Tariq Harb dismissed Maliki’s legal case against Abadi’s appointment.

Harb said: “The decision by the president to task Haider Al-Abadi to form a government was based on the constitution and relied on the democratic principle. The constitutionality of the decision was achieved by the fact that Abadi is a member of the largest parliamentary bloc, the State of Law coalition.”

He added that the democratic principle was also met by the fact that more than half the MPs belonging to the coalition had broken with Maliki and endorsed Abadi.