NAJAF, Iraq (Reuters) - Forced off Iraq's streets and with diminished political clout, what anti-American Shi'ite cleric Moqtada al-Sadr and his Mehdi Army militia do next will be crucial if they are to remain relevant. The rallying cry of the Mehdi Army and Sadr's political movement since the U.S.-led invasion in 2003 has been to kick American soldiers out of Iraq. With a 2011 deadline for a U.S. troop withdrawal possibly in sight, Sadr must find another cause to give his movement purpose and cohesion.
Sadr has largely frozen the Mehdi Army, which led two uprisings against U.S. forces in 2004, and has shifted to cultivating the cultural wing of his movement.
The cleric has huge support among Iraq's Shi'ite poor, and similar movements in the Middle East have traditionally replaced or bolstered armed struggle with cultural and charitable works that have fed into votes at the ballot box.
But the cleric has decided his movement will not compete in upcoming local elections under the Sadr banner. Sadrists will instead join independent candidate groups.
The move could be a way of keeping a hand in politics without giving legitimacy to elections held while U.S. forces are still in place.
But the move could limit their influence in increasingly powerful provincial councils, where they hold little sway after largely boycotting the last local elections in 2005, and rob them of momentum in national polls due at the end of 2009.
Sadrists took part in the previous parliamentary elections, but control only 10 percent of seats. They withdrew their six cabinet ministers from the government in 2007 in protest at Shi'ite Prime Minister Nuri al-Maliki's refusal to set a timetable for the withdrawal of U.S. forces from Iraq.
Sadr's movement is unlikely to survive as a purely cultural and charitable organization with no military or political clout, said Toby Dodge, an Iraq specialist at the International Institute for Strategic Studies in London.
"They'd disappear almost overnight if they did that. It would go against every model they're copying ... If they don't run (in elections) and demobilize their militia, what's the point of them? What's the unifying ideology?" he said.
SADR SLIPPING?
Sadr spokesmen say the cleric froze his militia partly to give Baghdad and Washington space to agree a security deal, now in its final stages of negotiation, that is likely to pave the way for a large-scale U.S. troop withdrawal by the end of 2011.
"If the agreement has positive points and a defined deadline then I'm sure we will support it," chief Sadr spokesman Salah al-Ubaidi said in an interview at the cleric's headquarters in the holy Shi'ite city of Najaf.
Ubaidi last month suggested the Mehdi Army would dissolve if the United States withdrew according to a defined timetable.
With violence in Iraq at four-year lows, the Pentagon will pull 8,000 soldiers out by February, leaving 138,000 troops.
But the Sadr movement will only outline its next move after the U.S. presence ends, not before, Ubaidi said.
Meanwhile, rival political groups are consolidating power, while a series of crackdowns by an increasingly assertive Maliki has forced the Mehdi Army from many of its former bastions.
Attacks on Shi'ites by Sunni militants, which drove many to Sadr's militia for support, have plunged. Criminal elements among the Mehdi Army's ranks have also frustrated Sadr.
"Moqtada may be beginning to feel that the Mehdi Army is becoming more of a liability than an asset," said Reidar Visser, an Iraq expert and editor of the www.historiae.org website.
Luwaa Sumaisem, head of the Sadr parliamentary bloc's political committee, said the movement had future political ambitions and wanted to be central in efforts to rebuild Iraq.
Focus on the Sadrist cultural wing, which defines itself as an "army of cultural and religious doctrine" that wages jihad on the "western and secular tide," could be considered a political move in preparation for the departure of U.S. forces, he said.
"That we don't have political ambitions, that may be for the moment. It's not our priority," he told Reuters.
RELIGIOUS AUTHORITY
Greater religious authority could be one way Sadr intends to retain relevance. Widely believed to be studying in Iran, Ubaidi said it would not be long before Sadr would enter the ranks of the Marjaiya, or senior Shi'ite Islamic clergy.
"The next key step for the Sadrist movement may relate to Sadr's religious status, and in particular whether he is going to make an attempt to act as a scholar with the ability to issue his own fatwas (religious edicts)," Visser said.
In Shi'ite-majority Iraq the Marjaiya have huge influence, although frosty ties with Iraq's top Shi'ite clergy mean it is unclear how much weight would be given to Sadr's fatwas.
Often ambiguous and sometimes contradictory, many of Sadr's frequent statements give few clues to his thinking.
Making few public appearances, Sadr may next appear when the U.S.-Iraqi security deal is signed, Ubaidi said. Until then, the support of at least some of Iraq's Shi'ite poor remains strong.
"Of course we hope for no more violence. Look at all these young men," said Abdul-Zahra Darwish, the brother of a slain Mehdi Army fighter as he stood among graves at a Sadrist cemetery in Najaf. "But I am ready to fight and die."
Iraq's prime minister raised the stakes in his showdown with followers of Shi'ite cleric Moqtada al-Sadr, saying in an interview broadcast on Monday they would be barred from elections unless their militia disbands.
NAJAF, Iraq (Reuters) - Powerful Iraqi Shi'ite cleric Moqtada al-Sadr, who has not been seen in public for months, issued an unusual statement on Friday explaining his absence to his followers and admitting splits in his movement. 
Followers of Iraqi cleric Moqtada al-Sadr accused Prime Minister Nuri al-Maliki of attacking them in order to appease his US allies Sunday and warned him his days in office might be numbered.