BAGHDAD – More followers of an influential Iraqi Shiite cleric on Monday joined a rally in central Baghdad to press lawmakers to vote on a Cabinet shakeup proposed by the prime minister amid a simmering political crisis that could jeopardize the country’s fight against the Islamic State group.

Police cordoned off a downtown square with razor wire and concrete blocks after hundreds of Muqtada al-Sadr’s supporters on Sunday erected camping tents for what’s expected to be a long sit-in. Some protesters waived Iraqi flags while others raised anti-corruption slogans.

Al-Sadr on Saturday issued an ultimatum to parliament to vote on a new government on Monday’s session.

“If these conditions are not met, then let it be known that the people will decide,” al-Sadr wrote in his warning.

The firebrand Shiite cleric was the main force behind pressuring al-Abadi to offer lawmakers last month a list of technocrats nominated for his new government. He also mobilized thousands in Baghdad and the country’s Shiite south to stage protests but political blocs have rejected the nominees.

A vote on a second list was delayed last week when some lawmakers staged a sit-in inside the parliament, demanding al-Abadi and the rest of the political leadership step down.

In a statement early Monday, al-Abadi called on parliament to convene “immediately to overcome obstacles and to take part in finding solutions for the challenges the country faces.”

The U.S. Defence Secretary Ash Carter arrived in Baghdad on Monday to talk to Iraqi leaders about beefing up Iraqi forces working to retake the northern city of Mosul, a critical goal in the effort to defeat the Islamic State group. Carter has said the United States is considering a number of options, including more airstrikes and American troops on the ground.

IS has established a key stronghold in Mosul, Iraq’s second largest city, and retaking it from the militants would be a significant victory for the Iraqis.