Sen. John McCain, Arizona Republican, said the White House would be committing "an error of historic proportions" if it doesn't accede to Gen. Stanley A. McChrystal's request for tens of thousands more troops in Afghanistan.

Meanwhile, Sen. Dianne Feinstein of California upped the pressure for a major Afghanistan troop surge from the Democratic side, saying it makes no sense to stay in Afghanistan and not grant the general the forces he says are necessary.

Mr. McCain said he doesn't think the United States can win in Afghanistan unless President Obama sends at least 40,000 more troops to augment the 68,000 scheduled to be there by year's end - as suggested by Gen. McChrystal, the top U.S. commander in Afghanistan...