As violence and US casualties mount in Iraq, President Bush is facing a precarious political situation at home - and a potentially critical moment in the presidential campaign.
Current polls suggest that public opinion on the conflict could be approaching a tipping point. While Americans have always been divided over the war, a majority has consistently held that the US made the right decision in deposing Saddam Hussein. But some polls now find a majority disapproving of Mr. Bush's handling of the situation in Iraq, and, according to a recent Pew survey, a sizable margin believes the administration does not have a plan to bring the conflict to a successful conclusion. The number of Americans calling for the troops to come home is rising, with just a bare majority now favoring keeping US troops in the region.
Bush has warned all along that the mission in Iraq would be long and difficult. He has also stressed that Iraq is a central front in the war on terror, and that success there is integral to America's safety - a view that has been key to maintaining public resolve.
But the president's decision to go to war has come under increasing fire in recent weeks, with officials such as former counterterrorism czar Richard Clarke charging that the effort in Iraq has actually undermined the war on terror.
As the situation on the ground has deteriorated, some Republicans, such as Sen. Richard Lugar, are questioning the administration's plan for turning over power to Iraqis, while Democrats such as Sen. Ted Kennedy are comparing the situation to Vietnam.
If unrest continues, public support for the mission could quickly crumble - and the political consequences for Bush could be severe.
"Opinion is very fluid right now," says Carroll Doherty, editor of the Pew Research Report. "There's a sense that things are perhaps spinning out of control - and that's a very dangerous perception."
White House allies say the current spate of violence in Iraq was to be expected as the June 30 deadline for transition of power approached, with angry minorities trying to thwart the launch of a democracy. They also say that the political landscape here will be affected much more by that pivotal event than by the various ups and downs of preceding months.
"Certainly, the news that has been coming out of Iraq has been disconcerting, and it's going to impact how people are thinking," says David Winston, a Republican pollster. "But, ultimately, the way they're going to judge this is by how the transition occurs."
The situation is markedly different from Vietnam, he adds, because Americans see the Iraq effort as part of the overall war against terrorism - and therefore feel they have a greater stake in the outcome. "Because of 9/11, this is not an abstraction. We can be attacked on our own soil, and that has created a very different context in terms of how we view things overseas."
But others argue that the Vietnam threat - the spread of communism - was actually more frightening to Americans than the threat posed by Iraq, particularly given the fact that no link has been established between Iraq and Al Qaeda, and no weapons of mass destruction (WMD) have been found.
To a San Francisco fireman passing through Chicago's O'Hare airport, this is another Vietnam. Buying a newspaper from one of the vending boxes that line the terminal, some with inch-high headlines on the newest battles in Fallujah, this Democrat in a blue work shirt says the war "was falling apart before it even got started." People are dying for no reason, he continues, "and I suspect whoever replaces Saddam Hussein will be as bad or worse. We have no right being there."
That said, many stalwart supporters of Bush and the war are unfazed. Connie Perreira, having breakfast with her husband on their way to their daughter's graduation from boot camp in Fort Jackson, is confident that "We're doing what we should be doing." Whether or not there were weapons of mass destruction, says the registered Independent, "They're taking care of the human rights issue." The death of American troops "makes me sad. But it has to be expected. That's war."
Still, if violence continues even after the transition, Americans could become increasingly impatient with the US occupation. "If there's a handoff and Americans still continue to die, then I think there will be a big erosion" of support, says John Mueller, an expert on war and public opinion at Ohio State University.
United Airlines worker Craig Pecora says his attitude - both on Bush and on the war - is already changing. Taking tickets for a plane bound for Wichita, Kansas, plane, the Republican says the whole enterprise is moving too slowly. "I thought it would take two or three months. I'm getting more impatient.... I'm glad we went in, but we just need to get it done."
The two primary critiques of Bush are these: By alienating allies, he has forced the US to bear virtually all the costs of the war in lives and dollars, and, more important, he seems to have no road map for bringing US troops home. The longer American troops stay in Iraq after the transition takes place, the more frustrated the public will get, critics predict. "People are going to say: Finally [Iraqis] took control, but we still can't get out," says Celinda Lake, a Democratic pollster.
To some extent, that sentiment may already be starting to take hold, now that the Pentagon is planning to extend tours of duty.
Still, while the public may be growing less happy with Bush's stewardship of the situation, it's not clear that his rival, Sen. John Kerry, will necessarily benefit.
While Kerry has criticized the president's handling of the conflict and said he would work to bring in more support from allies, Republicans charge that the Massachusetts senator has not offered specifics on how he would handle the situation differently.
The imperative for Bush in coming weeks will be to make clear that he does have a plan, say analysts. Americans will often support their president through foreign policy challenges - even crises - as long as they feel confident that he has a decisive solution to the problem.
"When there doesn't seem to be a decisive response from the top, that's when support erodes," says David Perlmutter, a professor at the Reilly Center for Media and Public Affairs at Louisiana State University.
• Ann Scott Tyson contributed to this report from Chicago.
To what extent do you agree or disagree with this statement:
"By invading Iraq, the Bush administration has neglected* the war on terrorism."
Agree strongly 20 %
Agree somewhat 18
Disagree somewhat 23
Disagree strongly 35
Source: Christian Science Monitor/TIPP poll
* Clarke said Bush, by invading, had 'greatly undermined' the war on terrorism.
How would you grade President Bush's performance in handling the Iraq situation?
January 2004 April 2004
Excellent 29 % 21 %
Good 24 21
Average 16 15
Poor 13 15
Unacceptable 16 28
Source: Christian Science Monitor/TIPP polls