(CNN) -- Anti-U.S. Shiite cleric Muqtada al-Sadr's bloc is threatening to withdraw support from Iraq's government if next week's planned meeting in Jordan between President Bush and Iraqi Prime Minister Nuri al-Maliki takes place.
Al-Sadr has been critical of U.S. actions in Iraq, and his faction blames the United States for creating the conditions that led to a bloodbath Thursday that killed more than 200 people in Baghdad's Shiite neighborhood of Sadr City.
The cleric's movement holds significant power in the Iraqi government, and the threat of a walkout could jeopardize the stability of al-Maliki's administration, which has relied on the support of both the United States and fellow Shiites.
Here is some key background about the Shiite cleric's life:Al-Sadr is the son of Grand Ayatollah Mohammed Sadiq al-Sadr, who was killed by Saddam Hussein's regime in 1999 along with two other sons. Baghdad's Shiite stronghold of Sadr City, previously known as Saddam City, was renamed for Mohammed Sadiq al-Sadr after the fall of Hussein.Al-Sadr is the leader of the militia group known as the Mehdi Army, which has opposed the U.S.-led coalition in Iraq. The number of Mehdi Army fighters is unknown, though estimates are in the thousands.In the chaos following Hussein's ouster in 2003, al-Sadr's followers established security and services in Baghdad's main Shiite neighborhood and in parts of southern Iraq.In 2004, al-Sadr's Mehdi Army fighters fiercely battled U.S.-led troops in Najaf, Iraq, from inside the Imam Ali shrine, one of the most holy places in Shiite Islam. That same year, Al-Sadr's forces also fought U.S. troops in Karbala, another city holy to Shiites.In April 2004, Iraqi officials issued an arrest warrant for al-Sadr in the 2003 killing of rival Shiite cleric Abdul Majid al-Khoei. Months later, the Iraqi interim government ruled against pressing murder charges.Al-Sadr has significant political clout in the Iraqi government. His party holds at least 30 seats in the 275-seat parliament, forming one of its largest voting blocs. Al-Sadr's movement also controls several government ministries. The Shiite-led Iraqi government has been under pressure to disband the Mehdi Army and other militias. Iraqi officials have been reluctant to take action against the militia in part because of the power of al-Sadr's bloc in parliament.