By Ross Colvin
WASHINGTON (Reuters) - President Barack Obama was set to announce on Friday he will pull U.S. combat forces from Iraq by August 2010, winding down the unpopular six-year war but leaving behind up to 50,000 troops.
Obama's decision to leave a sizable force to bolster stability was welcomed by congressional Republicans, including former presidential candidate Senator John McCain, while some Democrats were concerned too many troops would remain in Iraq.
The announcement fulfils a major campaign promise that Obama made last year as he concentrates on beefing up the U.S. military presence in Afghanistan to turn back the resurgent Taliban.
His visit to Camp Lejeune, a Marine Corps base in North Carolina, comes at the end of a long week in which he focussed on rebuilding the U.S. economy and unveiled a huge $3.55 trillion budget blueprint for fiscal 2010.
Obama's 19-month timetable marks a historic juncture in an unpopular war that has proven enormously costly to the United States and defined the presidency of George W. Bush. It has been a huge drain on the Treasury, cost the lives of some 4,250 U.S. soldiers and severely damaged America's standing in the world.
"The president will announce that the current combat mission in Iraq will end on August 31, 2010. At that point, the remaining forces in Iraq will undertake a new mission, a more limited mission," a senior administration official said, speaking on condition of anonymity.
Some 35,000 to 50,000 of the 142,000 U.S. troops now in Iraq will remain to train and equip the Iraqi forces, protect civilian reconstruction projects and conduct limited counterterrorism operations, the official said.
Key congressional leaders got a White House briefing on Thursday giving them details of the plan. Obama drew support from McCain, who on the campaign trail last year bitterly fought Obama's call to withdraw troops from Iraq.
"Senator McCain supports the plan to leave 50,000 troops in Iraq," said McCain spokeswoman Brooke Buchanan. She said McCain was going to speak about it on the Senate floor on Friday.
Key Democrats appeared cool to the plan.
Senate Majority Leader Harry Reid, asked about leaving 50,000 troops in Iraq, said on Thursday: "That's a little higher number than I had anticipated."
"WAY STATION"
House of Representatives Speaker Nancy Pelosi, a Democrat, in an MSNBC interview on Wednesday said she wanted to hear the president's justification for keeping 50,000 troops in Iraq.
Defence Secretary Robert Gates said whatever Obama decided would be "a way station" since all U.S. troops must be out of Iraq by the end of 2011 under an agreement negotiated with the Iraqi government.
He said "the thinking all along had been that any force left after we stopped combat operations would be focussed on the counterterrorism mission, on training, advising, assistance, and that sort of thing."
For many war-weary Americans, the Iraq war has been dramatically overshadowed by a deep recession that has left many struggling to make ends meet and millions jobless.
As U.S. troops draw down, Washington will put more focus on a regional diplomatic strategy and greater efforts to encourage Iraq's leaders to strengthen a fragile political stability to prevent a resurgence of the sectarian bloodshed that killed tens of thousands of Iraqis.
By the end of 2011, the aim is to have "zero" U.S. troops in Iraq, in line with a military pact signed between the two countries, the official said. Asked whether the drawdown was irrevocable, another official said Obama reserved the right to revisit any plans if it was in the U.S. national interest.
But with Obama planning to ramp up the U.S. military effort in Afghanistan and banking on using the Iraq troop reduction to help slash a ballooning $1.3 trillion (918 billion pounds) deficit, Stephen Biddle, a senior fellow at the Council on Foreign Relations, said once the drawdown began it would be "a one-way movement."
"The issue now is slow calendar-based versus fast-calendar based," he said.
The United States invaded Iraq in March 2003 after the Bush administration accused Saddam Hussein of hiding weapons of mass destruction. No such weapons were found and U.S. troops quickly became bogged down first in a bloody insurgency and then in civil strife between Shi'ite and Sunni Muslims. Violence has since sharply declined.
(Additional reporting by Thomas Ferraro and Susan Cornwell, writing by Steve Holland, editing by Vicki Allen)
