* General supports Obama plan for withdrawing U.S. troops
* No change seen in Pakistan in near future
By Missy Ryan
WASHINGTON, June 28 (Reuters) - The U.S. general poised to take command of Western forces in Afghanistan on Tuesday embraced President Barack Obama's plan to withdraw a third of U.S. troops, saying it can be done without undermining the war effort.
Lieutenant General John Allen, expected to be confirmed as commander of U.S. and NATO forces, stood in contrast to other top U.S. brass in his unqualified support for the plan to pull 33,000 troops from Afghanistan over the next 15 months.
"We have made really spectacular progress in the south ... We're going to consolidate that progress," Allen told members of the Senate Armed Services Committee.
"We anticipate we will continue to achieve the objectives of the campaign," he said, despite challenges from lawmakers who see long odds in the Obama administration's gamble to conduct the war with fewer troops and a tighter timeline.
Allen will replace General David Petraeus, who acknowledged that Obama's decision last week to pull the entire 'surge' force he sent to Afghanistan by September 2012 was a more aggressive step than he had recommended. [ID:nL3E7HN0LX]
Obama's top military advisors like Admiral Mike Mullen, chairman of the U.S. Joint Chiefs of Staff were unusually candid about Obama's plan. They said they had initially been uncomfortable with an accelerated drawdown, but ultimately backed it.
In Afghanistan, Allen will seek to repeat his experience as a commander in western Iraq in 2007-08, when tribal leaders' decision to join the fight against an al Qaeda spinoff group in Iraq helped the United States halt spiraling violence.
He said the reduction of U.S. soldiers would be blunted by the growth in Afghan forces, which are expected to increase by some 70,000 by the time the initial drawdown is completed by the fall of 2012.
That did not placate some lawmakers who see Obama's decision as rooted in political considerations rather than battlefield realities.
"After all that we've given to this mission, the money we've committed to it, the decade we have devoted to it and the precious lives we've lost in it, why would we do anything now that puts our mission at greater risk of failure?" asked Republican Senator John McCain.
Obama is keen to curtail the U.S. role in Afghanistan, which costs over $110 billion a year, as he faces pressure to cut spending and launches his 2012 re-election bid.
But the plan announced last week was attacked both by those who want U.S. troops home more quickly and those who fear a hasty exit will allow Afghanistan to unravel into lawlessness once more.
Allen, who until recently was deputy commander of U.S. Central Command, acknowledged he would face major challenges in Afghanistan, where the Taliban will seek to regain lost territory just as a shaky local army takes over in some areas.
A renewed Taliban blitz could make it even more difficult for the Obama administration to show headway in its nonmilitary campaign to shore up Afghanistan's weak government and encourage President Hamid Karzai to crack down on corruption.
Allen said he would advise Obama if the situation on the ground might warrant a change in the military plan.
Events in neighboring Pakistan will also be crucial to Allen's success in Afghanistan, and he expressed hope that leaders in Islamabad would step up efforts to disable militant groups such as the Haqqani network that operate from Pakistan's western tribal areas.
U.S.-Pakistani ties hit a low point after last month's secret U.S. raid that killed al Qaeda leader Osama bin Laden in Pakistan, fueling suspicions in Washington about the country's links to extremist groups.
Vice Admiral William McRaven, who also testified at the hearing as Obama's nominee to head U.S. Special Operations Command, said he didn't expect more Pakistani action against certain militant groups in the short term.
"I don't think it is likely to change," he said. "It is both a capacity issue for the Pakistanis and I think potentially a willingness issue." (Additional reporting by Phil Stewart; Editing by Vicki Allen) (For more coverage of Afghanistan and Pakistan, see: here))