The vote has been a key demand of Allawi as well as well populist cleric Moqtada Sadr who had threatened to organise mass protests outside parliament unless lawmakers backed the government in a vote this week.

After multiple meetings between parliamentary groups and key officials, including Allawi, parliament speaker Mohammed Halbusi postponed the session until Saturday.

The political wrangling coincides with unprecedented protests since October 1 in the capital and Iraq's south, demanding a complete government overhaul.

Prompting objections from protesters, political parties nominated Allawi as a consensus candidate this month, after President Barham Saleh threatened to unilaterally choose a premier if they failed to agree.

But two months after outgoing premier Adel Abdel Mahdi's government resigned under pressure from the street, lawmakers remain divided over the distribution of cabinet posts.

Another bone of contention is the fate of the 5,200 US troops stationed in Iraq, which Shiite lawmakers have voted to expel, over objection from their Sunni and Kurdish counterparts.