(CNN) -- President Barack Obama takes full ownership of the Afghanistan war Tuesday when he announces to a waiting nation his decision on sending more U.S. troops there.
The president will travel to the U.S. Military Academy at West Point, New York, for what is expected to be his second escalation of U.S. forces in Afghanistan since he came to power in January.
Obama is expected to send more than 30,000 U.S. troops and seek further troop commitments from NATO allies as part of a counterinsurgency strategy to wipe out al Qaeda elements and stabilize the country while training Afghan forces.
The expected new troop deployment would increase the total U.S. commitment there to almost 100,000 troops in Afghanistan, bolstered by about 45,000 NATO forces.
According to White House Press Secretary Robert Gibbs, the president's speech will explain why the United States is involved in Afghanistan, the new American mission in the war-torn country and the process that led to Obama's decision.
He also will emphasize the limit on U.S. resources in manpower and budget, and stress that the Afghan mission is not open-ended, Gibbs said.
The decision carries significant political risk for Obama, who will announce it nine days before he travels to Oslo, Norway, to accept the Nobel Peace Prize.
His liberal base, which helped him win last year's presidential election, opposes another troop deployment to Afghanistan.
"I think he's made up his mind that there needs to be a troop increase and I have to say I'm very skeptical about that as a solution," said Rep. Janice Schakowsky, D-Illinois, a longtime Obama ally who now worries Afghanistan will become what she calls another quagmire.
In addition, the deployment expected to cost $30 billion a year comes amid high unemployment as the economy emerges from a recession. That concerns Democrats and Republicans faced with competing domestic priorities such as health care reform and job creation.
Meanwhile, Republican opponents have been pressuring Obama to fulfill the request made more than three months ago by his commanding officer in Afghanistan, Gen. Stanley McChrystal, for 40,000 additional troops to carry out a counter-insurgency strategy.
Despite signals that Obama will send most of the forces sought by McChrystal, Republicans have criticized the president for what they derisively call "dithering" over the decision. White House officials and Democrats, along with top generals, defend the decision-making process as a deliberative analysis of the situation.
On Monday, Gibbs said the focus on Afghanistan differed from how the previous administration handled the war it started.
"We bore down on this in a way that I dare say had not been done," Gibbs said.
In Afghanistan, reaction to the possibility of more U.S. troops ranges from outright opposition to a willingness to see what happens.
"We welcome their arrival if they really expel the Taliban, terrorists, and al Qaeda from the borders of Afghanistan," said Mohammad Zia, 40, in Kabul, the capital. "But if they come and kill more civilians and destroy villages, then they shouldn't come."
Back home, Obama's allies said the president must convince the American public that sending more troops will help achieve the goals of the mission.
"The president needs to explain how more combat troops will speed up training of Afghan forces," Sen. Carl Levin, D-Michigan, said Sunday on the CBS program "Face the Nation".
The deployment won't work if the mission is for the United States to take on the Taliban on its own, Levin said. Gibbs said Obama has been briefing top aides, military officials and foreign leaders about this decision.
Obama previously ordered more than 20,000 additional troops to Afghanistan.
A defense official told CNN in recent weeks that the military had planning under way to send three additional Army brigades, totaling about 15,000 troops; a Marine brigade with about 8,000 troops; a headquarters element of about 7,000; and between 4,000 and 5,000 support troops -- a total of about 34,000 troops.
The troops would be dispatched throughout Afghanistan but would be focused mainly on the southern and southeastern provinces, where much of the recent fighting has taken place. CNN reported last month that this was the preferred option within the Pentagon.
There also is concern about the dollar cost of the war. House Appropriations Committee Chairman David Obey, D-Wisconsin, recently proposed a special war surtax to finance the conflict.
"If we're concerned about our future and the need for a shared sacrifice, then this is just simply a common sense approach," Rep. John Larson, D-Connecticut, said Monday on CNN's "American Morning". "The only people we're asking to sacrifice in this war effort have been the men and women who serve our armed services and do so valiantly. They deserve the same kind of commitment here at home from citizens."
Other Democrats -- as well as Republicans -- dismissed the idea.
"In the middle of this recession, I don't think you're going to be able successfully or fairly to add a tax burden to middle-income people," Levin said Sunday.
Gibbs told reporters Monday that he had "not heard extensive discussion" at the White House about a possible surtax.
"I know the president will touch on costs" during Tuesday's address, he said, but "I don't expect to get overly detailed (about that issue) in the speech."
U.S.-led troops first invaded Afghanistan in response to the al Qaeda terrorist network's September 11, 2001, attacks on New York and Washington. The invasion overthrew the ruling Taliban, which had allowed al Qaeda to operate from its territory -- but most of the top al Qaeda and Taliban leadership escaped the onslaught.
Taliban fighters have since regrouped to the mountainous region along Afghanistan's border with Pakistan, battling U.S. and Afghan government forces on one side and Pakistani troops on the other. Al Qaeda's top leaders, Osama bin Laden and Ayman al-Zawahiri, remain at large and are suspected to be hiding in the same region.
The conflict has so far claimed the lives of more than 900 Americans and nearly 600 allied troops.