BAGHDAD (Reuters) - The political power of anti-U.S. Shi'ite cleric Moqtada al-Sadr increases the pressure on Iraq's new government to reject any effort to extend a U.S. military presence after the last U.S. soldier leaves this year.
Sadr, a firebrand still capable of rousing millions of Shi'ite supporters, told a rapturous audience on Saturday to oppose the United States, using his first speech since returning from self-imposed exile in Iran to reaffirm his anti-U.S. credentials.
The scion of a powerful Shi'ite family led two uprisings against U.S. soldiers and his Mehdi Army militia was at the forefront of much of the sectarian violence unleashed after the 2003 U.S.-led invasion.
His militia has since laid down its arms and Sadr's movement has turned its sights on the political arena, garnering seven ministries in the new government and proving instrumental in securing a second term for Prime Minister Nuri al-Maliki.
That clout, and Sadr's presence, is likely to give Maliki even less room to manoeuvre at the end of 2011, when all U.S. forces must withdraw under a bilateral security pact but Iraq will not be ready to fully defend its borders from attack.
"Sadr will try to use his presence to stiffen the resolve of as many other Iraqi players as possible, including Maliki, to stick with the stated commitment that the United States should leave as planned," Wayne White, adjunct scholar from the Middle East Institute, said.
Maliki has said the joint security pact will not be renegotiated and that all U.S. troops, now numbering fewer than 50,000 compared to a peak of 170,000, must leave, but he has held open the possibility that the Iraqi parliament might approve some sort of extended presence if needed.
Iraq has built up sizeable new ground forces, under U.S. tutelage, but its fledgling air force will not be ready to defend the country until after it receives its first expected fighter jets in 2014.
Its military also continues to struggle against a stubborn insurgency, while Kurd-Arab tensions remain unresolved, leading to speculation that Maliki may have little choice but to ask the U.S. military, and particularly the U.S. Air Force, to stay on.
Any inclination by Maliki to extend the U.S. military presence would turn Sadr -- and Shi'ite voters -- against him.
"The Maliki government and most Iraqis will want to have a relationship with the United States that serves Iraq's national interests, while demonstrating at the same time that they are fully sovereign and independent," said David Mack, a former U.S. Ambassador and Middle East Institute scholar.
Since his arrival in the holy Shi'ite city of Najaf on Wednesday, Sadr has projected a more statesmanlike manner, removed from his role as a militant agitator in the past.
But his anti-U.S. rhetoric was unchanged.
The Shi'ite cleric called the United States, Britain and Israel "common enemies" and demanded that the government stick to its pledge to make all U.S. forces leave this year.
His stance will likely stir apprehension amongst Iraqis and Americans hoping the United States will be a powerful ally to the country it has had a significant foothold in, and spent considerable blood and money over, since ousting Sunni dictator Saddam Hussein.
U.S. officials say a military presence will be less important than a substantial diplomatic one in the future, but diplomatic interactions may also be constrained by Sadr's anti-U.S. influence over the government.
"The U.S. diplomatic, and security, presence will remain considerable for some years to come, but if Sadr does become a major political figure, as is likely, then this will make it less and less likely that the U.S. can exert influence from a position of strength," said Paul Rogers, a professor of peace studies at Britain's Bradford University.
Sadr's ties to U.S. foe Iran, which hosted him during his self-imposed exile and helped broker a deal between the Sadrists and Maliki, also unnerves those hoping for deep U.S. influence over Iraq in the coming years.
Additional reporting by Rania el Gamal; Editing by Michael Christie