One of Iraq's most powerful Shi'ite leaders, Abdul-Aziz al-Hakim, died in Iran on Wednesday after his health deteriorated while he was being treated for lung cancer. He was 59. Two senior clerics from his party, Sheiks Humam Hamoudi and Jalaleddin al-Saghir, told The Associated Press that he died after being hospitalized in critical condition in Tehran. In a brief announcement, Iranian state television also reported that al-Hakim died from lung cancer. Al-Hakim wielded enormous influence since the 2003 US invasion as head of the Supreme Islamic Iraqi Council, maintaining close ties to both the Americans and his Iranian backers. Al-Hakim was diagnosed with lung cancer in May 2007 after tests at the prestigious University of Texas M.D. Anderson Cancer Center in Houston. He chose to receive his chemotherapy treatment in Iran. Deputy parliament speaker, Shi'ite Khalid al-Attiyah, described his death as a loss for Iraq. "We offer our condolences to all the Iraqi people for the death of al-Hakim. He is one of the symbols of Iraq ... we hope political leaders will continue his work." His death comes two days after his party, SIIC, the largest Shi'ite grouping joined with followers of anti-US cleric Muqtada al-Sadr to form a new political alliance to contest January parliamentary elections. In a rare show of Shi'ite disunity, the new Iraqi National Alliance excluded Iraqi Prime Minister Nouri al-Maliki, dealing a major blow to his chances to keep his job at the helm of the country after the Jan. 16 vote. Al-Hakim has largely withdrawn from the public eye since being diagnosed with cancer. But he has groomed his son, Ammar, as his successor. Calm and soft-spoken, al-Hakim held no government post since Saddam Hussein's ouster, preferring to play the role of kingmaker. Al-Hakim had enormous influence in the turbulent years after Saddam's downfall. However, his close ties to Iran, where he lived in exile for more than 20 years, made him a controversial figure, distrusted by most Sunnis and even some Shi'ites as Tehran's man in Iraqi politics and a symbol of sectarian politics. Al-Hakim's outspoken support for Shi'ite self-rule in the south of Iraq also was seen by Sunnis and Shi'ites alike as an Iran-inspired plan to weaken the country and hand Tehran control of the country's Shi'ite heartland, home to most of Iraq's oil wealth and the riches of the shrine cities of Najaf and Karbala.