These arguments, or variations among them, are being made before President Obama and will confront him with a stark choice that could make or break his presidency. The president has said the conflict in Afghanistan is "a war of necessity," not a "war of choice."

A Pentagon spokesman, Geoff Morrell, said on TV after the president's meeting with his key advisors last week that it would take several weeks for a decision. "I would remind you," he said, "that the Bush administration when they were deliberating whether or not to surge forces into Iraq took about three months to come to that conclusion."

The latest poll by the reputable Pew Research Center shows that American support for keeping U.S. troops in Afghanistan has slipped to 50 percent, with 43 percent saying the troops should be removed. Republicans favor keeping troops in Afghanistan, Democrats for removing them, and independents almost exactly mirror the overall public position.

The U.S. military commander in Afghanistan, Gen. Stanley A. McChrystal, has delivered his assessment to the president and summarized it to an audience in London last week: "The situation is serious, and I choose that word very carefully. I would add that neither success nor failure for our endeavor in support of the Afghan people and government can be taken for granted. My assessment and my best military judgment is that the situation is, in some ways, deteriorating, but not in all ways."

McChrystal pointed to the construction of roads, provision of clean water, access to health care, children in school, and access to education for females. He added, however: "A tremendous number of villagers live in fear, and there are officials who either cannot or do not serve their people effectively. Violence is on the increase."

McChrystal said: "We need to reverse the current trends, and time does matter. Waiting does not prolong a favorable outcome. This effort will not remain winnable indefinitely, and nor will public support."

"The cruel irony," he concluded, "is that, in order to succeed, we need patience, discipline, resolve and time."

Two columnists in The New York Times reflected the national split over Afghanistan. David Brooks, a moderate conservative, wrote that there are "realistic choices for America's Afghanistan policy — all out or all in, surrender the place to the Taliban or do armed nation-building. And we might as well acknowledge that it's not an easy call. The costs and rewards are tightly balanced."

The next day, Bob Herbert, a liberal, wrote: "Americans are tired of the war."

He asserted: "After the long, sad experience in Iraq, and the worst economic shock since the Depression, they are not up for extended combat and endless nation-building in Afghanistan." He urged the president to "start bringing the weary troops home."

Richard Halloran, formerly a New York Times correspondent in Asia and in Washington, is a writer in Honolulu.