Military officials and others have been expecting Obama to settle on a middle-ground option that would deploy an eventual 32,000 to 35,000 U.S. forces to the 8-year-old conflict. That rough figure has stood as the most likely option since before Obama's war council meeting earlier this month when he tasked military planners with rearranging the timing and makeup of some of the deployments. That led to Monday night's final gathering.
With the war worsening on Obama's watch, U.S. combat deaths climbing and public support dropping, the president seemed aware he has a lot to explain to the public.
"I feel very confident that when the American people hear a clear rationale for what we're doing there and how we intend to achieve our goals, that they will be supportive," he said, speaking at a White House news conference with Indian Prime Minister Manmohan Singh.
"It is my intention to finish the job," he said of the war in Afghanistan that has been going on since shortly after the Sept. 11 attacks in 2001.
Obama held his 10th and final war council meeting Monday night. In response to a question about his upcoming announcement, he sketched out the areas - but not the specifics - of what he will talk about after Thanksgiving.
He suggested he intends to explain in some detail not only troop deployments and the other civilian and diplomatic elements of an overhauled strategy, but also how the U.S. might ultimately leave Afghanistan. When he ordered advisers to rethink the options presented to him, it was mainly to clarify when U.S. troops would turn over responsibility to the Afghan government and under what conditions.
"It's going to be very important to recognize that the Afghan people ultimately are going to have to provide for their own security, and so we'll be discussing that process whereby Afghan security forces are properly trained and equipped to do the job," Obama said.
Obama must not only sell his plan to the public, but to foreign allies whose additional resources the White House wants in Afghanistan. The president bluntly said Tuesday he would talk in his announcement about "the obligations of our international partners in this process."
The timing of his address is timed in part to come before a NATO foreign ministers meeting, taking place in Brussels, Belgium, at the end of next week.
Obama also must pitch his plan to Capitol Hill, where lawmakers will be asked to fund the effort.
Among those likely to take part in congressional hearings are Obama's top commander in Afghanistan, Gen. Stanley McChrystal, as well as Secretary of State Hillary Rodham Clinton, Defense Secretary Robert Gates and U.S. Ambassador to Afghanistan Karl Eikenberry. All four were among about 20 officials and advisers participating in the president's final deliberations Monday night - one of the biggest groups gathered for these sessions in some time.
"It is in our strategic interests, in our national security interest to make sure that al-Qaida and its extremist allies cannot operate effectively in those areas," Obama said of the Afghan war. "We are going to dismantle and degrade their capabilities and ultimately dismantle and destroy their networks."
Reflecting the waning popular support for continued - or escalated - war, Democrats are coming to dislike the conflict in greater numbers. Democratic allies of the president, such as House Speaker Nancy Pelosi, D-Calif., and Senate Armed Services Chairman Carl Levin, have become more outspoken on the war in recent days.
The force infusion expected by the military would represent most but not all the troops requested by McChrystal, for a retailored war plan that blends elements of the commander's counterterror strategy with tactics more closely associated with the CIA's unacknowledged war to hunt down terrorists across the border in Pakistan.
McChrystal presented options ranging from about 10,000 to about 80,000 forces, and told Obama he preferred an addition of about 40,000 atop the record 68,000 in the country now, officials have said.
Obama has already ordered a significant expansion of 21,000 troops since taking office.
The additional troops would be concentrated in the south and east of Afghanistan, the areas where the U.S. now has most of its forces, military officials said. The new troops that already went this year were directed to help relieve Marines stretched to the limit by far-flung postings in Helmand province and that would continue, while the U.S. effort would expand somewhat in Kandahar.
The increase would include at least three Army brigades and a single, larger Marine Corps contingent, officials said. All officials spoke on condition of anonymity because the decision is not final.
U.S. war planners would be forgoing the option of increasing U.S. fighting power in the north, a once-quiet quadrant where insurgents have grown in strength and number in the past year. But McChrystal's recommendation never called for a quick infusion there.
In the absence of large additions of ground forces, dealing with the north would probably require relying more heavily on air power, two military officials said. Any such additional air strikes would be more successful if, as U.S. officials hope, Pakistan turns up the heat on Taliban militants on their side of the border.
As originally envisioned by McChrystal, the additional U.S. troops would begin flowing in late January or after, on a deployment calendar that would be slower and more complex than that used to build up the Iraq "surge" in 2007. McChrystal's schedule for full deployment has it taking nearly two years, military officials said.
The relatively slow rollout is largely driven by logistics. But it also could give the White House some leverage over Afghan President Hamid Karzai. U.S. officials note that where and how fast troops are deployed are a means to encourage fresh and more serious efforts at cooperation and clean government in Afghanistan.