Iraqi Prime Minister Adel Abdul Mahdi has 10 days to finalise cabinet formation, populist cleric Muqtada Al Sadr said on Monday night, as pressure mounts on the premier to take action to end Baghdad’s political deadlock. Mr Sadr, who leads parliament’s largest bloc, warned that his supporters would take a “new stance” against the government of Mr Abdul Mahdi if politicians fail to vote on key vacant positions. "I call on all political blocs to charge the prime minister with completing the cabinet formation process within 10 days," Mr Al Sadr said in a letter released by his office. "Otherwise we will have another position … and you are aware of our stance,” said the statement. Mr Al Sadr was referring to the potential withdrawal of support for Mr Abdul Mahdi. The Iraqi premier assumed office in October, but has failed to form the required 22-minister cabinet and to assert his influence over the two dominant political blocs in parliament – Islah and Binaa. The Saairun party of Mr Al Sadr, which gained the majority of votes during last May’s general elections, leads the Islah bloc. The Binaa bloc is led by Hadi Al Amiri's political alliance Fatah and includes the political wing of the Iran-linked Popular Mobilisation Forces, an umbrella group of militias that were formed to fight ISIS. The power struggle between the two rival groups has foiled efforts to form the Iraqi government. Mr Al Sadr has called for independent candidates to be put forward for several key cabinet positions, including interior, defence, education and justice roles. But they remain vacant due to a dispute with the Binaa bloc. Binaa has pushed interior candidate Falih Al Fayyadh, who is linked to Iran-backed militias. Mr Al Sadr, a nationalist who rejects the involvement of both the United States and Iran in the country’s internal affairs, was quick to oppose the nomination. The cleric's militia, previously known as the Mahdi army (which bears no relation to Prime Minister Abdul Mahdi), staged various violent uprisings against US forces after the 2003 invasion to remove former dictator Saddam Hussein. He was described at the time as the biggest security threat in Iraq by officials in Washington in Baghdad. Yet Mr Al Sadr made a surprise victory in the May vote by promising to fight corruption and improve services. The 10-day deadline follows mounting criticism directed towards the premier. A third bloc, Hikma, led by Shiite cleric Ammar Al Hakim, announced on Sunday that it intends to become the opposition after failing to win many seats or hold much influence over Prime Minister Abdul Mahdi. The opposition's role is to make life "less pleasant" for the premier, Utica Risk Services Iraq expert Kirk Sowell told <em>The National</em>. Some political actors are choosing to distance themselves from the government, which is viewed as failing, so they can position themselves better for next year's provincial elections, likely to take place next April.