LATEST DEVELOPMENTS

• Iraqi Prime Minister Nouri al-Maliki refused to step down after Iraq’s president formally nominated a replacement, signalling a potential power struggle.

• Military units loyal to al-Maliki took up positions around Baghdad, the capital.

• Fighting elsewhere in Iraq against the Islamic State insurgents continued, with the U.S. making fresh airstrikes.

• In northern Iraq, Kurdish fighters who had been pushed back by the Islamic State began receiving weapons deliveries, said to be from the CIA, and made progress in pushing the insurgents out of a string of towns near Irbil, the Kurdish capital.

Iraq’s political crisis deepened Monday, with Prime Minister Nouri al-Maliki ordering military units to take up positions in the capital while the coalition his political party belongs to nominated a rival to succeed him as head of the government.

President Fouad Massoum selected Haider al-Abadi, Parliament’s deputy speaker, to replace al-Maliki as prime minister, asking him to form a new government within 30 days.

Al-Maliki, however, showed no sign he intended to give up his grip on the power, and it was difficult to predict how the struggle would end.

President Barack Obama welcomed new leadership in Iraq as “a promising step forward” Monday amid a political and security crisis in Baghdad, saying the only lasting solution is the formation of an inclusive government.

Obama did not mention al-Maliki but clearly was addressing the embattled incumbent as he called for Iraqi political leaders to work peacefully through a political transition.

“These have been difficult days in Iraq,” Obama said outside his rented vacation home on Martha’s Vineyard. “I’m sure there are going to be difficult days ahead.”

Obama’s remarks came as the U.S. conducted more airstrikes against the advance of Islamic State militants in northern Iraq. In Washington, Lt. Gen. William Mayville, the director of operations for the Joint Chiefs of Staff, told reporters that the 15 targeted strikes have slowed the Islamic State’s advance but done little to degrade the militants’ capacity as a fighting force.

“In the immediate areas where we’ve focused our strikes we’ve had a very temporary effect,” Mayville said. “I in no way want to suggest that we have effectively contained — or that we are somehow breaking the momentum of the threat posed by” the Islamic State group.

It was unclear how the political crisis in Baghdad would affect Iraq’s military effort against the Islamic State. Al-Maliki’s government will remain in place until Abadi announces a new one and receives approval from Parliament.

Al-Maliki’s Dawa political party appeared split on whether to continue backing him — al-Abadi also is a member of Dawa — but the expected delay in naming a government and then winning Parliament’s approval, perhaps as long as six weeks, could provide al-Maliki with time to win support from other Shiite Muslim factions and thwart al-Abadi’s efforts.

Al-Abadi “only represents himself,” Khalaf Abdul-Samad, who like al-Maliki and al-Abadi is a Dawa member, said at a televised news conference.

Dawa allies from the Badr Organization, another Shiite political grouping, said they, too, had opposed al-Abadi’s selection. Badr’s leader, Hadi al-Amiri, told Iraqi media he did not sign on to al-Abadi’s nomination.

Al-Abadi pledged to move quickly “to protect the people.”

The National Iraqi Alliance, a coalition of Shiite political parties that includes Dawa, chose al-Abadi as prime minister less than a day after al-Maliki announced that he would take Massoum to court over alleged constitutional violations.

Al-Maliki also consolidated elite Iraqi troops around the sprawling government complex known as the International Zone late Sunday. Soldiers and police stood guard at many street corners, some on foot and some in trucks mounted with machine guns.

To outsiders, the troop movements looked suspiciously like an effort to intimidate al-Maliki’s opponents, and the United Nations issued a statement urging the soldiers not to disrupt the political process.

Al-Maliki opponents decried the troop deployments. “The prime minister is getting kind of crazy,” said Kurdish lawmaker Serwan Abdullah Ismail.

But others saw nothing nefarious in the troop movements, including al-Abadi, who described the deployments on Twitter as “in anticipation of security threats.”

Earlier in the day, Secretary of State John Kerry said al-Maliki’s actions could lead the U.S. to withhold further military assistance just days after American jets and drones began launching airstrikes against the insurgents.

“One thing all Iraqis need to know, that there will be little international support of any kind whatsoever for anything that deviates from the legitimate constitutional process that is in place and being worked on now,” he said.

For months, U.S. officials have urged al-Maliki to step down, contending that his divisive leadership stood in the way of unifying the country against Islamic State militants who since June have seized territory in Iraq’s northern and western regions.