FORT HOOD, Texas - President Barack Obama's deliberations over war strategy in Afghanistan have narrowed to four options but a decision is still weeks away, the White House said on Tuesday.

The president will have an opportunity to discuss four options with his national security team tomorrow, Obama's spokesman, Robert Gibbs, told reporters aboard Air Force One.

He declined to say what they were.

Officials described Wednesday's White House meeting, which will bring together Obama's top military and civilian advisers, as critical to a decision after two months of deliberations.

The officials, speaking on condition of anonymity because of the sensitivity of the matter, said Obama was considering options that included sending roughly 15,000, 30,000 or 40,000 more troops to Afghanistan to try to stem Taliban gains.

Currently, there are nearly 68,000 U.S. troops and 40,000 allied forces in Afghanistan.

Anybody who tells you the president has made a decision ... doesn't have, in all honesty, the slightest idea what they are talking about. The president has yet to make a decision, Gibbs said en route to a memorial service at an Army base in Texas where 13 people were shot dead by a gunman last week.

WEAKENED PUBLIC SUPPORT

Record combat deaths have eroded U.S. public support for the war in Afghanistan, and a decision to expand troop levels could become a political liability for the president ahead of congressional elections next year.

In a letter to Obama dated Wednesday, when the United States will mark Veteran's Day, a group of senior Republican senators urged Obama to immediately authorize the deployment of the troops that the U.S. and NATO commander in Afghanistan, General Stanley McChrystal, requested.

Over 68,000 Americans are already serving in harm's way in Afghanistan, and the sooner we can provide the reinforcements and resources they need, the safer and more successful they will be, the senators wrote.

In his confidential troop request, McChrystal argued that 40,000 additional troops were needed to help secure Afghan population centers and to give NATO some additional resources to take on Taliban and al Qaeda fighters in outlying areas, officials said.

But officials have described a 30,000-troop increase as a leading option. Washington hopes to convince NATO allies to at least send additional trainers for the Afghan army and police. Those contributions could bring the total to nearly the 40,000 that McChrystal recommended.

Any deployment of additional forces next year would likely start by spring and stretch into late 2010.

Brigades generally include 3,500 to 4,000 troops, though they can swell to over 5,000 troops if other units are attached. Marine brigades can be larger.

(Additional reporting by Adam Entous; Editing by Cynthia Osterman)

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