WASHINGTON — President Obama’s national security team is contemplating troop reductions in Afghanistan that would be steeper than those discussed even a few weeks ago, with some officials arguing that such a change is justified by the rising cost of the war and the death of Osama bin Laden, which they called new “strategic considerations.”

These new considerations, along with a desire to find new ways to press the Afghan president, Hamid Karzai, to get more of his forces to take the lead, are combining to create a counterweight to an approach favored by the departing secretary of defense, Robert M. Gates, and top military commanders in the field. They want gradual cuts that would keep American forces at a much higher combat strength well into next year, senior administration officials said.

The cost of the war and Mr. Karzai’s uneven progress in getting his forces prepared have been latent issues since Mr. Obama took office. But in recent weeks they have gained greater political potency as Mr. Obama’s newly refashioned national security team takes up the crucial decision of the size and the pace of American troop cuts, administration and military officials said. Mr. Obama is expected to address these decisions in a speech to the nation this month, they said.

A sharp drawdown of troops is one of many options Mr. Obama is considering. The National Security Council is convening its monthly meeting on Afghanistan and Pakistan on Monday, and although the debate over troop levels is operating on a separate track, the assessments from that meeting are likely to inform the decisions about the size of the force.