The 54-year-old lawmaker and former Najaf governor was nominated Tuesday to be Iraq's new prime minister, the second attempt to replace outgoing premier Adel Abdel Mahdi this year.

Zurfi has 30 days to form a cabinet, which must earn a vote of confidence from Iraq's 329-member parliament.

But several Shiite blocs have already signalled their displeasure with the way Zurfi was selected.

On Wednesday, the State of Law coalition, led by ex-prime minister Nuri al-Maliki, and lawmakers linked to the relatively moderate cleric Ammar al-Hakim said they opposed the president's unilateral selection of the prime minister.

President Barham Saleh, they insisted, should have referred to parliament's largest bloc to select a nominee.

The powerful Fatah bloc, the political arm of the Hashed al-Shaabi military network, had also slammed Zurfi's nomination as unconstitutional.

Along with some smaller parties, those opposed could add up to more than 100 lawmakers voting against a Zurfi-led cabinet.

One key Shiite leader, cleric Moqtada Sadr, said Wednesday he would not announce a position on Zurfi's nomination.

Kurdish and Sunni blocs, meanwhile, will likely be supportive of the candidate.

Zurfi was a longtime member of the Dawa party, the historic opposition force to dictator Saddam Hussein, who was ousted in a 2003 US-led invasion.

A dual US-Iraqi national, Zurfi spent roughly a decade in the United States and returned after the invasion to serve as governor of his native city of Najaf under the US-dominated occupying force.

Respected as a statesman focused on improving public services and security, many hope he could shelter Iraq from spiralling tensions between Tehran and Washington.

In his first public statement late Tuesday, Zurfi pledged to hold elections within a year of forming his cabinet and vowed to respond to the demands of protesters hitting the streets for months over government graft and inefficiency.

He also promised to improve security in the country, which has seen more than two dozen rocket attacks targeting foreign installations since late October.

But his programme made no mention of a parliament vote earlier this year to order the departure of thousands of foreign troops deployed across Iraq.

The vote was a response to a US drone strike that killed top Iranian general Qasem Soleimani and deputy Hashed chief Abu Mahdi al-Muhandis in Baghdad on January 3.

Hardline Iraqi factions with close ties to Tehran had reportedly conditioned their support of any new prime minister on his willingness to enforce the decision.