Iraqi Shi'ite cleric Moqtada al-Sadr urged political blocs on Monday to pressure the prime minister to form a complete cabinet within 10 days, warning that his supporters would take a "new stance" if they failed to do so.
Sadr, who leads a large parliamentary bloc, has rallied his supporters to stage mass protests against previous governments, and has implied this could take place against the current government of Prime Minister Adel Abdul Mahdi.
"I call on all political blocs to charge the prime minister with completing the cabinet formation process within 10 days," Sadr said in a letter released by his office.
"Otherwise we will have another position ... and you are aware of our stance."
Sadr's Saeroon political bloc came first in a May 2018 general election. He has called for independent candidates to be put forth for several key cabinet positions which remain vacant over disagreement between powerful parties.
Abdul Mahdi began his term in October, but has yet to fill interior and defense posts.
Sadr, who presents himself as a nationalist who opposes the involvement of both the United States and Iran, Iraq's two mains allies, scored a surprise victory in the May vote by promising to fight corruption and improve services.
The other largest political bloc includes candidates backed by Iran who have tried to push an interior candidate linked to Iran-backed militias.
A wild card in Iraq's turbulent politics driven largely by sectarian interests, he has frequently mobilized tens of thousands of followers to protest against government policies and corruption.
His militia, previously known as the Mehdi Army, staged two violent uprisings against US occupation forces after the invasion. Iraqi and US officials described him at the time as the biggest security threat in Iraq.