The ABC News/Washington Post poll found that 66 percent of respondents oppose the war. Support for the effort is at its lowest level ever and has dropped below the lowest point in support for the Iraq war.
While Republicans remain far more supportive of the Afghanistan mission than Democrats and independents, only 44 percent said they now believe the war is worth fighting. That is a low point while support among the other groups is a few points higher than their record lows.
Attitudes toward the mission have often turned sharply because of external events. The Afghanistan mission was almost as unpopular a year ago and then support increased sharply after the killing of Osama bin Laden.
Opposition increased after the Koran burnings and the protests that followed among Afghans. It jumped 6 percentage points after the Kandahar massacre when a U.S. soldier allegedly targeted Afghan civilians.
While approval of the war is down 13 points, approval of President Obama's handling of Afghanistan has dropped only 5 points. His overall approval rating has improved to 50 percent.
Langer Research Associates interviewed 1,003 adults by telephone last Thursday to Sunday. The margin of error is 4 points for the full sample.