BY ANNE GEARAN

Associated Press

WASHINGTON -- President Obama's top military adviser endorsed an increase in U.S. forces for the worsening war in Afghanistan on Tuesday, setting up a split with leading Democrats in Congress and complicating an already-tough decision for the president himself.

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, said the war is growing more complicated and the enemy gaining in sophistication. Winning will require more resources from outside Afghanistan, including more troops, Mullen told Congress.

"A properly resourced counterinsurgency probably means more forces, and without question, more time" and dedication, Mullen said.

Gen. Stanley McChrystal, the U.S. commander in charge of both American and NATO forces in Afghanistan, delivered a grim assessment of the war to Washington last month and is expected to follow up soon with a request for thousands of additional troops and more equipment.

That will leave Obama to decide whether to expand a war that polls say is rapidly losing public support in the U.S. and drawing pointed criticism in Congress. He has already roughly doubled the size of the American military force in Afghanistan since taking office, with only limited gains to show. Obama has an ambitious strategy to turn around a war that will soon enter its ninth year, and his aides say the plan needs time to work.

Sen. Carl Levin of Michigan, chairman of the Senate Armed Service Committee, warned the White House last week that he does not want to see a request for more troops until the United States takes bolder action to expand Afghanistan's own armed forces.