WASHINGTON - With only three weeks left before U.S. military forces are scheduled to begin withdrawing from Afghanistan, the debate over the size and pace of that withdrawal has become increasingly intense.

Ryan Crocker, President Obama's choice to become ambassador to Afghanistan, appeared before a Senate panel Wednesday. But as the debate rages in Washington, the sad reality is that the war drags predictably on and on. (By J. Scott Applewhite, AP)On one hand, the Pentagon, backed by prominent neo-conservatives and other hawks, insists that the 18-month-old "surge" of 30,000 U.S. troops has turned the strategic tide against the Taliban.

Anything more than a "modest" drawdown of a few thousand of the nearly 100,000 soldiers and marines there through the end of the year, they argue, risks losing all that has been gained.

"I would hope that (the withdrawal) is very small," the 2008 Republican presidential candidate, Sen. John McCain, told the Financial Times this week. "I would hope that it is 3,000. We need another fighting season (against the Taliban)."

On the other hand, President Barack Obama's political advisers, backed by a strong majority of Democrats and a small but growing minority of Republicans in Congress, are arguing for a much more substantial withdrawal.

In the clearest marker so far, the influential chairman of the Senate Armed Services Committee, Carl Levin, said this week that at least 15,000 troops should be withdrawn between July and the end of the year.