From hiding, possibly in Iran, radical anti-American Shiite cleric Muqtada al-Sadr is believed to be honing plans to sweep into the power vacuum made all the more intense by news that his chief Shiite rival has lung cancer. And he's betting the U.S. won't keep its troops in Iraq much longer.

Al-Sadr aides and loyal lawmakers have told The Associated Press the cleric's ambitions mean he will avoid taking on the Americans militarily as he did in 2004, when his Mahdi Army militia fought U.S. forces to a standstill.

Instead, the 33-year-old cleric plans to keep up the drumbeat of anti-American rhetoric, consolidate political gains in Baghdad and the mainly Shiite south, and quietly foster even closer ties with neighboring Iran and its Shiite theocracy.

The strategy is based in part on al-Sadr's belief that Washington will soon start pulling out troops or draw them down significantly, leaving behind a huge hole in Iraq's security and political power structure, al-Sadr's associates said.

Iraqi Defense Minister Abdul-Qader al-Obeidi told reporters Monday that Iraq's military is drawing up plans in case U.S.-led forces leave the country quickly.

"The army plans on the basis of a worst-case scenario so as not to allow any security vacuum," al-Obeidi said. "There are meetings with political leaders on how we can deal with a sudden pullout."

It was unclear whether al-Obeidi was referring to routine contingency planning, or if his remarks reflected a new realization among Iraqi leaders that the days of American support may be limited.

Al-Sadr also believes, his associates said, that Shiite Prime Minister Nouri al-Maliki's government may not last much longer, given its failure to improve security, services and the economy. A government collapse is certain to be followed by a political realignment in which the Sadrist movement stands a good chance of emerging as the main player. Al-Sadr's loyalists have 30 of parliament's 275 seats.

The six lawmakers and aides spoke to the AP in separate interviews over the past week. Several agreed to speak of the movement's future only on condition of anonymity because they are not authorized to discuss strategy with outsiders. They stuck to broad outlines, declining to be drawn into specifics.

"We gave the government a historic opportunity, but al-Maliki did not use it and that's why we are preparing for a state led by the Sadrist movement," said an al-Sadr political aide who is among those who spoke on condition of anonymity. "An Islamic state led by the Sadrists is our future," he said.

The impact of such a plan — if implemented — would be far reaching.

An Iraq with ultra-radical Sadrist Shiites holding dominant power would seek to curb U.S. influence and bolster the influence of clergy-ruled Iran throughout Iraq and possibly outside its borders in the Sunni Arab heartlands of Saudi Arabia, Syria and Jordan.

It also could deepen the Shiite-Sunni divide and unleash a wave of Shiite militancy with offshoots joining forces with like-minded groups, such as Lebanon's Hezbollah.

Al-Sadr is said by U.S. officials to have been in Iran since he dropped out of sight some three months ago and is widely believed to be increasingly relying on Iran as the main sponsor of his movement.

After weeks of claiming the cleric was back in the Iraqi holy city of Najaf, his backers now concede al-Sadr is, in fact, in Iran.

"Without Iran, the U.S. can crush the Sadrist movement," said Vali Nasr, a prominent U.S.-based expert on Shiite affairs. "When you have 50,000 to 60,000 fighters, you need a sponsor like Iran," said Nasr, alluding to the reported strength of the Mahdi Army.

Moving closer to Iran now would be a timely tactic since Tehran's main Iraqi client, the Supreme Islamic Council of Iraq, is widely thought to have forged closer ties with the United States and used a key party conference this month to adopt a new creed stating its commitment to Western values like human rights and democratic rule.

The Supreme Council's leader, Abdul-Aziz al-Hakim, has been diagnosed with lung cancer and is in Iran for chemotherapy treatment. His illness removes from the scene, at least temporarily, a major al-Sadr rival.

Al-Sadr's Mahdi Army militiamen have frequently fought with the Council's own private army — the Badr Brigade — in southern Iraq, an oil-rich region where the two groups compete for dominance.

A preview of a Sadrist-led Iraq can be found in Sadr City, a crowded Baghdad district where some 2.5 million Shiites live under the virtual governance of the Sadrists and the Mahdi Army.

Islamic Sharia courts operate freely in the neighborhood. Girls as young as 7 are forced to wear the Muslim veil. Stores selling alcohol have been forcibly shut. Religious punishments, like flogging those who violate Islam's ban on alcohol, are routine.

"We want an Islamic system," said Nassar al-Rubaie, a Sadrist lawmaker. "We want a presidential system that will produce someone with a power similar to that of a Muslim caliph."

Much of the Sadrists' resolve to create an Islamic society, according to the lawmakers and aides, has to do with the movement's strong messianic convictions. In Shiite terms, this translates into making society sufficiently pure for the return of the so-called Hidden Imam, a descendant of Islam's Prophet Muhammad who disappeared as a child in the 9th century. Shiites believe he will return one day to bring justice to Earth.

"The hidden imam is our savior," said Amer al-Husseini, a cleric and a senior aide to al-Sadr in Baghdad. "We need to prepare for his return, both ideologically and practically."

To that end, al-Sadr yanked his five ministers from al-Maliki's unpopular government last month and ordered his Mahdi Army militia to go underground while the U.S. military stages what is likely to be its last major bid to quiet the capital.

Sadrist lawmakers, meanwhile, are pushing to have parliament adopt a decision demanding a timetable for the withdrawal of U.S.-led foreign troops.

Al-Sadr, from his Iranian exile, also has made overtures to the once-dominant Sunni Arabs of Iraq.

On Tuesday, Sadrist lawmakers met with Sunni Arab tribal leaders leading a fight against militants from al-Qaida in Iraq in the western Anbar province. In a joint statement, the two sides called for local elections to be held soon and for Iraq's rival political blocs to rise above their differences.

"We believe that the Sadrist movement is an independent and nationalist movement that we are ready to cooperate with," said Omar Abdul-Sattar, a lawmaker from the Iraqi Islamic Party, the nation's largest Sunni group.

But a Sadrist-led push to introduce a strict version of Islam in Iraq would be a bitter pill to swallow for Sunnis who account for about 40 percent of the population. Most Sunnis — Arab and Kurd alike — disapprove of the dominant role by the clergy in Shiism and view some Shiite rituals, like self-flagellation, as idolatry.

Nor is the Sadrist theology especially popular among other Shiites in Iraq.

Shiites living in areas under Mahdi Army control often complain of the heavy-handedness of the militiamen in enforcing Islamic tenets but grudgingly accept their sway because they see them doing a better job than security forces in protecting their neighborhoods from attacks by Sunni militants.

Nevertheless, Sadrist lawmakers Ghofran al-Saadi and Saleh al-Aujaili said the movement plans to vigorously contest the next local elections to wrest control of provincial councils from rival Shiite groups that benefited from the Sadrists' decision not to take part in the January 2005 vote. The Sadrists fielded candidates only in the parliamentary part of the election.

Holding local elections is one of several policy benchmarks that Washington wants al-Maliki's government to meet to ensure continued U.S. support, but no date has been set yet.

"We have a huge popular base and we are not going to let that go to waste," al-Saadi said. "We have a duty to meet the aspirations of our supporters."