WASHINGTON (AFP) – President Barack Obama will announce the size of his drawdown of US troops from Afghanistan on Wednesday, mapping out an endgame for a 10-year war that has exacted a fearsome human and financial toll.

Two administration officials said Obama would reveal the fruit of his deliberations on a pullback due to begin next month, in a pivotal moment for US war strategy and his own political prospects ahead of his reelection bid.

"The Afghanistan speech will be on Wednesday," one official said, on condition of anonymity, as Obama moved closer to a final decision on the size of the withdrawals and the future US footprint on Afghan soil.

The president must decide the pace and size of reductions to a 30,000-strong troop escalation which he ordered surged into the conflict in December 2009, a deployment which brought the US garrison to 100,000 soldiers.

Some analysts also expect him to chart a clear glidepath of withdrawals which will lead up to the planned assumption of security control of Afghanistan by the country's nascent defense forces in 2014.

Obama will also be expected to explain to Americans that his surge has wrought slow, but significant progress, particularly in southern Afghanistan against the Taliban and foreshadow operations in key eastern districts.

White House officials also say that since Obama came to office, and poured new resources into a war that they say was neglected by the George W. Bush administration, there has been significant progress against Al-Qaeda.

In December 2009, Obama laid out a new war strategy designed to disrupt, dismantle and defeat Al-Qaeda, break the momentum of the Taliban and to offer the Afghan government space to move towards a security takeover.

"We have made significant progress towards achieving those goals," White House spokesman Jay Carney said Monday.

"Obviously, the most sensational and significant data point in that progress, of that progress, is the elimination of Osama bin Laden," he said.

"But there has been enormous progress in disrupting and dismantling al-Qaeda in the Afghanistan-Pakistan region beyond and below Osama bin Laden."

Obama will be operating on shifting political ground however, with growing demands in Congress for significant troop withdrawals and mounting public disquiet with a war launched after the September 11 attacks in 2001.

Outbursts critical of US troops as "occupiers" by President Hamid Karzai have fueled skepticism over the Afghan government.

The difficult yet essential US marriage of convenience with anti-terror ally Islamabad is also under scrutiny after it was pushed close to breaking point by the special forces which killed bin Laden on Pakistani soil in May.

The White House indicated that Obama's decision was near when it scheduled a visit for him to Fort Drum Army base in upstate New York on Thursday, which houses the 10th Mountain Division, which has had repeated Afghan deployments.

In the run-up to Obama's long-awaited troop decision, the political ground appears to be shifting away from the Pentagon's apparent urging for a token drawdown towards a slightly more substantial troop reduction timetable.

Some Pentagon sources have pushed for a cut of only 5,000 or so troops.

But some key players on Capitol Hill want a much larger withdrawal.

The National Journal reported on Monday that war commander General David Petraeus would back a decision to bringing all of the 30,000 surge troops home only by the end of 2012.

The website said that Petraeus wanted to bring home one brigade combat team of 5,000 troops by the end of this year, and another by next spring.

Such a solution would allow a portion of the surge force to remain at the front during the next two warm weather fighting seasons.

Obama however has to weigh rising popular discontent over the war with military and strategic considerations and may want to showcase faster withdrawals when he runs for a second term next year.

US Defense Secretary Robert Gates, typically cautious about pulling out of Afghanistan too rapidly, appeared to signal some flexibility on Sunday.

"Whatever decision he makes we will have a significant number of troops remaining in Afghanistan," he told CNN, while adding in a nod to domestic pressure on Obama: "The drawdown must be politically credible here at home."