WASHINGTON — President Obama will spell out a costly Afghanistan war expansion to the public today, coupling an infusion of as many as 35,000 more troops with a vow that there will be no endless U.S. commitment.

Obama's first orders have already been made: at least one group of Marines will be deployed by Christmas.

Obama has said that he prefers "not to hand off anything to the next president" and that his strategy will "put us on a path toward ending the war."

The president will end his 92-day review of the war with a nationally broadcast address from the U.S. Military Academy at West Point, N.Y., in which he will lay out his revamped strategy. He spent part of yesterday briefing foreign allies in a series of meetings and phone calls.

Before Obama's call to British Prime Minister Gordon Brown, Brown announced that 500 more U.K. troops would arrive in southern Afghanistan next month — making a British total of about 10,000 in the country. And French President Nicolas Sarkozy, whose nation has more than 3,000 soldiers in Afghanistan, said French troops would stay "as long as necessary" to stabilize the country.

Obama's plan includes sending 30,000 to 35,000 more American forces into Afghanistan in a graduated deployment over the next year, on top of the 71,000 already there. There also will be a fresh focus on training Afghan forces to take over the fight and allow the Americans to leave.

He also will deliver a deeper explanation of why he believes the U.S. must continue to fight more than eight years after the war was started following the Sept. 11 attacks by al-Qaida terrorists based in Afghanistan. He will emphasize that Afghan security forces need more time, more schooling and more U.S. combat backup to be up to the job on their own, and he will make tougher demands on the governments of Pakistan as well as Afghanistan.

"This is not an open-ended commitment," White House press secretary Robert Gibbs said. "We are there to partner with the Afghans, to train the Afghan national security forces, the army and the police so that they can provide security for their country and wage a battle against an unpopular insurgency."

Obama was not expected to offer specifics on how much the additional $30 billion to $35 billion cost will increase the federal deficit, how long the U.S. commitment will continue and how it will wind down.

Gibbs said detailed discussions on costs would be held later with lawmakers.

DEPLOYMENT ORDERS

Even before explaining his decision, Obama told the military to begin executing the force increases. The president gave the deployment orders Sunday night, during an Oval Office meeting in which he told key military and civilian advisers of his final decision.

At least one group of Marines is expected to deploy within two or three weeks of Obama's announcement and will be in Afghanistan by Christmas, military officials said. Larger deployments will begin early next year.

The initial troop infusion is a recognition by the administration that something tangible needs to happen quickly, officials said. The immediate addition of Marines will provide badly needed reinforcements against Taliban gains in the southern Helmand province.

Obama's overall review was launched Aug. 31, when Army Gen. Stanley McChrystal, then the newly installed top U.S. commander in Afghanistan, delivered to Pentagon brass his assessment of the situation on the ground and what was needed to turn it around. McChrystal also produced a separate resource request, first seen by Obama on Oct. 1. The president's review was anchored by 10 extensive war council meetings, starting on Sept. 13, that featured a debate between a counterinsurgency strategy focused on protecting the local population and building up the Afghanistan government or a more limited counterterrorism strategy.

The final product is neither, though it leans more toward counterinsurgency.

The length of the process drew sharp barbs. Less than two months in, former Vice President Dick Cheney accused Obama of "dithering," beginning a drumbeat of criticism from Republicans. The White House shot back that the administration Cheney helped lead had given inordinate attention to Iraq while turning its back on Afghanistan.

But with U.S. casualties in Afghanistan sharply increasing and little sign of progress, the war Obama once liked to call one "of necessity," not choice, has grown less popular with the public and within his own Democratic Party.

In recent days, leading Democrats have talked of setting tough conditions on deeper U.S. involvement, or even staging outright opposition.

BIPARTISAN WORRIES

The displeasure on both sides of the aisle is likely to be on display when congressional hearings on Obama's strategy get under way later in the week.

Obama spent much of Sunday and yesterday on the phone, outlining his plan for the leaders of France, Britain, Germany, Russia, China, India, Denmark, Poland and others. He also met at the White House with Australian Prime Minister Kevin Rudd.

A briefing for dozens of lawmakers was planned for today, before Obama left for New York to give his speech against a military backdrop.

He also was to call Afghan President Hamid Karzai and Pakistan President Asif Ali Zardari — two leaders on whom the success of the plan will depend heavily.