Support among Americans for the Iraq war began to slip just weeks after US troops breached Baghdad and toppled the statue of Saddam Hussein. But since last fall, the downward slope has become precipitous, with doubts spreading from Democrats and independents into the Republican core of support.
As the nation takes stock of a war it embarked on four years ago Tuesday, those who regret that decision now outnumber supporters by 14 percentage points. Accelerating the slide, say opinion analysts, were bipartisan criticisms of US war policy by the Iraq Study Group and concerns that the mission has been obscured by civil war.
To some, the tumble in support simply shows weak knees, a lack of resolve in the American character. To others, it suggests a fall-off in trust of the Bush administration.
Opinion analysts, though, give a more nuanced picture, noting that the public is continually reevaluating the stakes in Iraq â€“ and assessing whether the costs of sticking with the fight have become higher than the stakes are worth.
It's a calculation with which Kathy Gier of Hutchinson, Kan., is all too familiar.
"I think a civil war is going on there, and it makes me profoundly sad," says Ms. Gier, a Republican. Some 55 percent of Republicans have come to the same conclusion on civil war, according to a Harris Poll in January.
This mother of three speaks supportively of her daughter's past service in Iraq as an Army helicopter pilot. "I was more adamant [that the war] was the right thing when she was there," she says during a phone interview.
But Gier no longer sees the wisdom of the invasion, a change of heart that came slowly and imperceptibly. "I thought it was the right the thing to do for a really long, long time, and I think it's pretty evident that it didn't work," she says, though she holds out hope for a "limited democratic process" and doesn't want to abandon the government there.
On the eve of the conflict, Gier had reservations about the reasons for going to war. "I supported the president's decision because I kept thinking that he must know more than we do."
Democrats and independents with similar doubts before the war trusted President Bush far less, making support from both groups softer. But the partisan divide in public opinion â€“ evident almost from the war's onset â€“ has also helped Mr. Bush carry those who trust his leadership through evolving justifications for the war, says Gary Jacobson, a political scientist at the University of California at San Diego.
"There's a huge partisan division on the war, and it's far larger for this war than for any previous military engagement going back to World War II," says Dr. Jacobson.
Republicans form a large majority of the 40 percent of Americans who stand by the decision to go to war, versus the 54 percent who do not, according to the Pew Research Center in Washington. Until recently, GOP support has held fairly steady in the face of the long exodus of independents and the early departure of Democrats.
In an address Monday, Bush urged Americans to be patient. The mission to help the Iraqi government secure its capital will take months, and fewer than half the troop reinforcements being sent have arrived in Baghdad, he said.
The presidential plea isn't likely to carry much weight with Keith Fraser, a Demo- crat whose support for the war faded long ago. "I wasn't a strong believer for very long, probably that first year," says Mr. Fraser, a retired naval officer in Swanzey, N.H. "I really look back upon it as being a very naive time for me."
Mr. Fraser did not vote for Bush in either election. But on the eve of the Iraq war, he found himself cautiously optimistic that the invasion would take care of a troubled situation left unresolved from Operation Desert Storm. And Colin Powell's presentation before the United Nations stirred up anxieties lingering from 9/11, he said in a phone interview.
"The absence of WMD [weapons of mass destruction] was the first chink in the armor," says Fraser. "Once you start to question that, then you begin to question other things, like was Al Qaeda sitting at the right arm of Saddam Hussein? You just began to wonder, is everything you're hearing the truth?"
Failure to find WMDs also affected Frank Hilts, a retired cop from Stone Mountain, Ga. Early in the war Mr. Hilts believed that invading Iraq not only was morally right, but also that it was crucial for national security and the war on terror.
After it became clear that no major caches of WMDs would be found in Iraq, Hilts, an independent who voted for Bush in 2000, went from cautious support to outright calls for impeachment, for shielding the "real" reasons for going to war as well as for mishandling the operation.
The view that the Bush administration deliberately misled the public about WMDs has become more pervasive over the course of the war and is now held by 54 percent of the public, according to a CNN/Opinion Research poll this month.
"It isn't really our war anymore," says Hilts, adding that Americans are now stuck refereeing a civil war.
Good news from Iraq has boosted support for the war at different junctures â€“ although temporarily. The capture of Mr. Hussein, elections, and the killing of the leader of Al Qaeda in Iraq, Abu Musab al-Zarqawi, all caused spikes in war support.
The spikes, say analysts, represent public reevaluation of either the costs or the benefits of the war, or both. Support rose after the first Iraqi election in January 2005. Voter turnout exceeded expectations, boosting Americans' optimism about the prospects for democracy in Iraq.
Optimism about progress plays a big role in the public's weighing of a war's costs and benefits, says Christopher Gelpi, a Duke University professor who studies US public opinion and the use of force.
"The rising costs [of war] matter a lot, if you're not making a lot of progress. The rising costs matter less if you are making a lot of progress," says Professor Gelpi. "There have been a few good events that have punctuated the scene from time to time, but that has all occurred against a steady backdrop of bad news all the time."
Until recently, the war's true believers have not been affected much by that steady drumbeat of bad news.
"Those who think the war is a good idea have a much more optimistic notion of the progress on the ground than those who don't," says Jacobson at UC San Diego. "But among Republicans ... optimism has really slid dramatically since September."
The share of Republicans who say the war is going well has fallen from 77 percent to 51 percent over the past year, according to Pew. That decline in Republicans' optimism spells trouble, according to Gelpi's model, for future support levels of the war.
Others look at the very short-term impact of good news in Iraq and suggest that the rising toll â€“ in the form of casualties â€“ plays a more decisive factor. But the White House can take little comfort in this view, too, because modern US history shows that war support declines over time as casualties mount.
The public-opinion trend lines for the wars in Iraq, Vietnam, and Korea follow a remarkably similar pattern, notes John Mueller, author of "War, Presidents, and Public Opinion." The Iraq war has seen many fewer casualties than the other conflicts, yet public backing has fallen by about the same amount. To Dr. Mueller, that's evidence that the American public values the Iraq conflict less than previous wars.
Those who are steadfast in their commitment to the war find a deeper meaning for it. Brian Green, a truck driver from Jacksonville, Fla., voted for Bush twice and still supports his efforts on the war on terror, a framework into which he says Iraq fits.
But Mr. Green's hopes for success â€“ which would be a stable Iraq and only a few remaining US troops â€“ waver often, depending on events there. "You go back and forth depending on the day," says Green, who votes independent. "But it's still absolutely the correct thing to do."
The one constant â€“ Bush's determination to finish the job â€“ is what inspires Green's support. "People forget how serious this is," he says. "Right now, it's just a popularity contest over who hates Bush more, and that kind of politics is just sickening."
â€¢Patrik Jonsson contributed to this report.
March 20: War begins with airstrikes on Baghdad.
April 9: US forces capture Baghdad and topple the statue of Saddam Hussein.
April 16: 74.1 percent of Americans say invading Iraq was the right decision.
May 1: From the deck of the USS Abraham Lincoln, President Bush announces an end to "major combat operations" in Iraq.
Aug. 19: At least 24 killed in a suicide bombing at the UN headquarters in Iraq.
Sept. 22: 63.1 percent of Americans say the war was the right decision.
Dec. 14: Announcement of Hussein's capture.
March 8: The Iraqi Governing Council signs an interim constitution.
April 4: US forces launch a first assault to capture Fallujah.
April 30: Images of the Abu Ghraib prisoner abuse are released.
May 8: Contractor Nicholas Berg is beheaded on videotape.
June 28: The US transfers sovereignty to an interim Iraqi government.
Aug. 10: 53.6 percent of Americans say the war was the right decision.
Sept. 7: American death toll in Iraq reaches 1,000.
Oct. 7: Iraq Survey Group releases the Duelfer Report, which says investigators found no evidence of stockpiled weapons of mass destruction at the time of the invasion.
Nov. 9: US and Iraqi forces begin the second battle for control of Fallujah.
Jan. 30: Elections held throughout Iraq. Turnout is higher than expected.
Feb. 21: 47.3 percent of Americans say the war was the right decision.
March 31: The elected Iraqi National Assembly meets for the first time.
Aug. 31: 956 killed and 465 hurt in a stampede on a bridge in Baghdad during a religious ceremony after rumors of a suicide bomber cause panic among the crowds.
Oct. 10: A majority of Americans â€“ 50 percent â€“ now say the war was the wrong decision.
Oct. 25: Referendum on Iraq's new constitution passes.
Oct. 26: American death toll reaches 2,000.
Dec. 15: Iraqis vote to elect a new parliament.
Feb. 22: Bombing damages the Golden Dome mosque in Samarra, one of Shiite Islam's holiest shrines.
June 8: Abu Musab al-Zarqawi, leader of Al Qaeda in Iraq, is killed.
Nov. 4: 48.1 percent of Americans say the war was the wrong decision; 45 percent say it was the right one.
Dec. 6: Iraq Study Group releases its re port.
Dec. 30: Hussein is executed.
Dec. 31: American death toll reaches 3,000.
Jan. 10: Bush outlines his plan for a troop buildup to improve security.
Sources: American Enterprise Institute, Pew Research Center