President Donald Trump has threatened to end US support for Iraq if former Prime Minister Nouri al-Maliki wins power again.
Maliki, who has links to Iran, was selected at the weekend by an alliance of Shia-led parties as its nominee for prime minister.
The US president wrote on Truth Social that Maliki would be a "very bad choice", adding: "Last time Maliki was in power, the Country descended into poverty and total chaos."
Maliki, whose time in office between 2006 and 2014 was marked by sectarian violence, stepped down after Islamic State seized large parts of the country.
After being endorsed by a Shia coalition known as the Coordination Framework on Saturday, Maliki would then normally be nominated by the president, who holds a largely ceremonial role.
