In the latest survey, more than four-fifths of Republicans viewed the war as justified, while more than four-fifths of Democrats and 54% of independents said it was not.
"Since there are no weapons of mass destruction in Iraq, I have doubts that it was worth it, especially considering the amount of resentment and distrust that this has caused, not only with our allies but in the whole Muslim world," said Ray Luechtefeld, a professor at the University of Missouri.
The poll underscores how attitudes about the war loom as a dividing line in the presidential election. Among those who think the threat from Iraq justified war, Bush leads Sen. John F. Kerry, the presumptive Democratic presidential nominee, 83% to 13%. Among those who think the war was not justified, Kerry leads, 84% to 11%.
Expectations are limited for the Iraqi interim government. Nearly two-thirds of those polled said they did not think the interim government would be able to govern the country without help from the U.S. and its allies.
And many are pessimistic that the Iraqis can sustain a democratic government: 38% think it is likely Iraq will maintain a democracy after the U.S.-led coalition forces leave, while 49% consider it unlikely.
Nearly three-fifths said Bush's Iraq policies had hurt America's image abroad; one in five thought they had improved attitudes toward the U.S.
Such concerns have eroded confidence in Bush's management of the war. Just 44% said they approved of Bush's handling of the war; in March, that figure was 51%. In the new poll, 35% said he had outlined a clear plan to succeed in Iraq.
Asked about his handling of the Abu Ghraib prisoner abuse scandal, 41% approved and 37% disapproved.
Kerry has faced criticism from some in his party for not offering a more distinct alternative to Bush's Iraq policy. In a sign that Kerry's position is murky to many voters, the poll found 15% said he had offered a clear plan on how to handle the situation, while 34% said he had not, and the rest did not know.
But another question pointed to the opening for Kerry created by doubts about Bush's direction. Voters split almost in half when asked if they accepted Kerry's contention that Bush had lost so much credibility around the world that only a new president could "rally the support of U.S. allies to help stabilize Iraq."
