People display a portrait of Iraqi Prime Minister Nuri al-Maliki as they gather in his support in Baghdad yesterday. Photo: Reuters

Iraq’s President named a new Prime Minister to end Nuri al-Maliki’s eight-year rule yesterday, but the veteran leader refused to go after deploying militias and special forces on the streets, creating a dangerous political showdown in Baghdad.

Washington, which helped install Maliki following its 2003 invasion that toppled Saddam Hussein, congratulated Haidar al-Abadi, a former Maliki lieutenant who was named by President Fouad Masoum to replace him.

But Maliki’s Dawa Party declared his replacement illegal, and Maliki’s son-in-law said he would overturn it in court. Washington delivered a stern warning to Maliki not to “stir the waters” by using force to cling to power.

A Shi’ite Muslim Islamist, Maliki is blamed by his erstwhile allies in Washington and Tehran for driving the alienated Sunni minority into a revolt that threatens to destroy the country.

Leaders of Iraq’s Sunni and Kurdish communities have demanded he go, and many fellow Shi’ites have turned against him.

Maliki himself said nothing about the decision to replace him, standing in grim-faced silence yesterday next to a member of his Dawa Party, who read out a statement on national television declaring Abadi’s nomination illegal.

Abadi “represents only himself”, the Dawa member, Khalaf Abdul-Samad said.

Maliki’s son-in-law Hussein al-Maliki told Reuters his camp would fight the “illegal” decision: “We will not stay silent. The nomination is illegal and a breach of the constitution. We will go to the federal court to object.”

Washington made its support for the new leader clear. The White House said Vice President Joe Biden relayed President Barack Obama’s congratulations to Abadi in a phone call.

We all have to cooperate to stand against this terrorist campaign launched on Iraq

“The prime minister-designate expressed his intent to form a broad-based, inclusive government capable of countering the threat of the Islamic State of Iraq and the Levant,” the White House said in a statement, using a previous name for the Sunni militant group that now calls itself the Islamic State. The new political crisis comes just days after Washington launched its first military action in Iraq since pulling its troops out in 2011.

US warplanes have bombed Sunni insurgents from the Islamic State, who have marched through northern and western Iraq since June.

Washington says it is taking limited action to protect a Kurdish autonomous region and prevent what Obama called a potential “genocide” of religious minorities targeted by the militants.

The fighters made new gains against Kurdish forces despite three days of US air strikes, while Baghdad, long braced for the Sunni fighters to attack, was now tensing for possible clashes between Maliki and rivals within the Shi’ite majority.

President Masoum asked Abadi to form a government that could win the support of all groups in a parliament elected in April. In remarks broadcast on television, Masoum, a Kurd, urged Abadi to “form a broader-based government” over the next month.

Abadi urged national unity against the “barbaric” Islamic State, which has driven tens of thousands from their homes as it swept aside Baghdad’s troops to consolidate a “caliphate” in Iraq and Syria.

“We all have to cooperate to stand against this terrorist campaign launched on Iraq and to stop all terrorist groups,” he said in broadcast remarks after meeting Masoum.

As police and elite armed units, many equipped and trained by the United States, locked down the capital’s streets, Secretary of State John Kerry aimed a stark warning at Maliki against fighting to hold on to power.

“There should be no use of force, no introduction of troops or militias in this moment of democracy for Iraq,” Kerry said.

“The government formation process is critical in terms of sustaining stability and calm in Iraq and our hope is that Mr Maliki will not stir those waters.”