WASHINGTON - President Barack Obama plans to announce a redrawn battle plan for Afghanistan, including what the military says could be a roughly 50 percent increase in U.S. forces, in a national address Tuesday night from the U.S. Military Academy.

Although military and administration officials cautioned that Obama has not settled on a final figure, the military is planning for an increase of up to 35,000 troops begin next year. Military officials spoke on condition of anonymity because they are not authorized to discuss the president's plans.

The additional forces would come atop a record 71,000 U.S. troops in the country now and would represent the largest expansion since the war began eight years ago.

Obama will be speaking to a war-weary American public, with the Army's storied academy at West Point, New York, as a backdrop and cadets entering the service most stretched by two wars on hand. Polls show support for the war has dropped significantly since Obama took office, with a majority now saying both that they oppose the war and that it is not worth fighting.

Congressional Democrats may be an even tougher sell. The administration is deploying two Cabinet officials and the nation's highest-ranking military officer to explain the new Afghanistan plan in Capitol Hill hearings to begin Wednesday.

The president promised this week to "finish the job" begun eight years ago, and press secretary Robert Gibbs said Wednesday the announcement would include an exit strategy. But the surge in troops would be Obama's second since taking office, and liberal Democrats already are lining up against it, in part because of the also-surging cost -- up to $75 billion a year.

Secretary of State Hillary Rodham Clinton, Defense Secretary Robert Gates and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, are expected to appear before the Senate Armed Services and House Foreign Affairs committees on Wednesday. On Thursday, they would go before the Senate Foreign Relations and House Armed Services committees.

Congressional Democrats, including House Speaker Nancy Pelosi, have been blunt in saying Congress has little stomach for a large troop increase and flagging confidence in the U.S.-backed Afghan government the war effort is meant to support.

Pelosi and about 17 other congressional leaders from both parties were invited to the White House for a meeting with Obama late Tuesday before he goes to the military academy in New York.

Congressional Republicans, in particular, are more eager for the testimony that is likely to come the following week. War commander Gen. Stanley McChrystal and the U.S. ambassador to Afghanistan, Karl Eikenberry, are likely to appear on Capitol Hill on Dec. 8 or 9, officials said.

Obama approved 21,000 additional troops for Afghanistan last spring, in what he said at the time was a wholesale rethinking of U.S. strategy for a war he said his predecessor had neglected. That brought U.S. troop force to an expected 68,000 by the end of this year. The actual figure is slightly higher now because of overlap between troops entering and leaving the country on regular rotations. The new troops Obama is expected to add would probably not begin to arrive until February or March.

NATO countries are also preparing to send more soldiers, with British Prime Minister Gordon Brown saying 10 NATO nations are ready to offer about 5,000 more troops. Britain, which has 9,000 troops in Afghanistan, the second-largest contingent after the United States, has not named the countries it claims will provide the extra troops.

Gibbs said Obama's recent meetings with military advisers have often focused on how to train Afghanistan's police and army to secure and hold areas taken from the Taliban so that U.S. forces can leave. "We are not going to be there another eight or nine years," he said.

Incompetence and corruption in the Afghan government have aided a rise in the Taliban's strength. The military strategy is expected to include specific dates that deployments could be slowed or stopped if necessary, a senior military official said.

The president and his top military and national security advisers have held 10 meetings to discuss future U.S. steps in Afghanistan. McChrystal has asked the president for about 40,000 troops, arguing that a robust but temporary surge was the best way to end the war.