"US Mission Iraq extends its best wishes to Prime Minister-Designate Ali al-Zaidi as he works to form a government capable of fulfilling the hopes of all Iraqis for a brighter and more peaceful future," the embassy posted on X.

"We stand in solidarity with the Iraqi people aspiring to the shared objectives of safeguarding Iraq's sovereignty, promoting security free from terrorism," it added.

Five months on from legislative elections, Iraq's President Nizar Amede nominated businessman Zaidi as prime minister-designate on Monday, giving him the daunting task of putting a cabinet together in the next 30 days amid fierce political wrangling.

The nomination came after months of deadlock during which US President Donald Trump threatened to cut all support for Iraq if two-time former premier Maliki returned to office.

The Coordination Framework -- the majority bloc in parliament and an alliance of Shia groups with varying ties to Iran -- had backed Maliki but then yielded to the US pressure.

After intense talks, it endorsed Zaidi on Monday, paving the way for his nomination to form a government, while Maliki was forced to drop out.

A political source told AFP that the framework backed Zaidi "after checking" with US representatives.

Following the 2003 invasion of Iraq that overthrew former ruler Saddam Hussein, the US has held major sway in the country. But the invasion also paved the way for neighbouring Iran to build its influence.

Since then, Iraq's leaders have struggled to balance relations between Washington and Tehran.

Iraq's new premier will be expected to address Washington's longstanding demand that Baghdad disarm Iran-backed groups, which the US designates as terrorist organisations.

During the Middle East war, which was ignited by a joint US-Israeli attack on Iran, these groups targeted US interests in Iraq and across the region.