Hundreds of Iraqi demonstrators, most of them followers of the Iraqi Shia leader Muqtada al-Sadr, have stormed the parliament building in Baghdad to protest against the nomination for prime minister by Iran-backed parties.

No lawmakers were present in parliament when the protesters penetrated the capital’s high-security Green Zone, home to government buildings and diplomatic missions, on Wednesday.

Only security forces were inside the building and they appeared to allow the protesters in with relative ease.

The protesters oppose the candidacy of Mohammed Shia al-Sudani, a former minister and ex-provincial governor, who is the pro-Iran Coordination Framework’s pick for premier.

Prime Minister Mustafa al-Kadhimi called on the protesters to “immediately withdraw” from the Green Zone.

He warned in a statement that security forces would see to “the protection of state institutions and foreign missions, and prevent any harm to security and order”.

Al-Sadr’s bloc won 73 seats in Iraq’s October 2021 election, making it the largest faction in the 329-seat parliament.

But since the vote, talks to form a new government have stalled and al-Sadr has stepped down from the political process.

Supporters of al-Sadr protest inside the parliament building in Baghdad

Protesters on Wednesday carried portraits of the Shia leader.

Riot police earlier used water cannons to repel demonstrators pulling down cement blast walls. But many breached the gates to the area. The demonstrators walked down the Green Zone’s main thoroughfare, with dozens gathering outside the doors to the parliament building.

Riot police assembled at the doors to the main gates. Demonstrators crowded around two entrances to the Green Zone, with some scaling the cement wall and chanting, “Al-Sudani, out!”

Al Jazeera’s Mahmoud Abdelwahed, reporting from Baghdad, said the protesters had come from “many cities” across Iraq.

“They want to convey their message that they are against corruption, against corrupt politicians,” he said.

“They say the country has suffered many years of corruption and mismanagement … they say they will continue to protest peacefully here.”

Hours after his followers occupied parliament, al-Sadr issued a statement on Twitter telling them their message had been received, and “to return safely to your homes,” signalling there would be no further escalation to the sit-in.

Shortly after, protesters began making their way out of the parliament building with security forces supervising.

The incident, and al-Sadr’s subsequent show of control over his followers, carried an implicit warning to the Framework party of a potential escalation to come if the government forms with al-Sudani at the helm.

Some protesters carried portraits of the Shia leader

Al-Sudani was selected by State of Law leader and former Prime Minister Nouri al-Maliki. Before al-Sudani can face parliament to be seated officially as prime minister-designate, parties must first select a president.

Al-Sadr exited government formation talks after he was not able to corral enough lawmakers to get the majority required to elect Iraq’s next president.

By replacing al-Sadr’s lawmakers, the Framework leader pushed ahead to form the next government. Many fear doing so also opens the doors to street protests organised by al-Sadr’s large grassroots following and instability.

In 2016, al-Sadr supporters stormed the parliament in a similar fashion. They staged a sit-in and issued demands for political reform after then-Prime Minister Haidar al-Abadi sought to replace party-affiliated ministers with technocrats in an anti-corruption drive.

Yerevan Saeed of the Arab Gulf States Institute in Washington told Al Jazeera that al-Sadr wanted to demonstrate to his rivals that he’s still “politically relevant” through the protests on Wednesday.

“Obviously, it is a very dangerous game. It could plunge the country into intra-Shia civil strife,” he said.

The political turmoil has left Iraq without a budget for 2022, holding up spending on much-needed infrastructure projects and economic reform.

Iraqis say the situation is exacerbating a lack of services and jobs even as Baghdad earns record oil income because of high crude prices and has seen no major wars since the defeat of ISIL (ISIS) five years ago.