Hundreds of them gathered in front of the oil ministry in Baghdad on Sunday, among them oil workers in orange jumpsuits waving lanterns to protest against oil and electricity shortages.
"The demonstration we are holding here today is aimed at showing what the mood of the Iraqi people is," said Shaikh Malik al-Kinani, who heads the al-Sadr office in the Baghdad neighbourhood of Kakh.
"It is very disturbing to see politicians only interested in elections. Instead they should be focusing on meeting the basic needs of the people," he said.
Dire economic situation
Thousands joined similar protests in the Shia heartland south of Baghdad on Saturday.
By invoking the dire economic situation and singling out the ever-worsening fuel shortages, al-Sadr's movement is tapping into an issue that strikes a chord with most of the population, especially among poor Shia, its power base.
For many Iraqis conditions have
not improved since the invasion
Nearly two years after the US invasion, many Iraqis complain that they have seen no improvement to their daily lives after 12 years of the sanctions imposed by the United Nations on Saddam Hussein's government.
Al-Sadr is not running in the 30 January general elections, but members of his entourage have thrown their weight behind the front-running list of Shia leader Abd al-Aziz Hakim.
The Unified Iraqi Alliance, which groups several parties representing the Shia, is widely expected to dominate the vote and also has the blessing of Grand Ayat Allah Ali al-Sistani, the leading Shia authority in Iraq.
Many al-Sadr supporters will back
Hakim (above) in the elections
On Sunday, the senior cleric reiterated his support for the list, despite complaints from rival parties that his backing was a case of religious interference with the electoral process.
"Grand Ayat Allah Ali al-Sistani stresses the need to hold the elections at the scheduled date and confirms his support for list 169," one of his aides said on Sunday, in reference to the Unified Iraqi Alliance.
"All Iraqis should take part in this process, which is the cornerstone of the new Iraq from which a new legitimate and elected government will emerge," Shaikh Najah al-Abbudi said.
Sunni Arab parties want the elections to be postponed until some degree of stability is restored.
The government will declare a holiday for the 30 January vote and impose tight restrictions on movement, including a total ban on vehicles around polling stations, State Minister for the Governorates Wail Abd al-Latif said on Saturday.
Abd al-Latif acknowledged that the threat of attacks had compromised preparations for the poll in four of Iraq's 18 provinces.
US-led troops will be relegated to a supporting role, US military spokesman Brigadier-General Erv Lessel said last month, providing "quick reaction forces and back-up forces".