An overwhelming majority of Americans believe that fighting between Sunni and Shiite Muslims in Iraq will lead to civil war, and half say the United States should begin withdrawing its forces from that violence-torn country, according to the latest Washington Post-ABC News poll.

The survey found that 80 percent believe that recent sectarian violence makes civil war in Iraq likely, and more than a third say such a conflict is "very likely" to occur. These expectations extend beyond party lines: More than seven in 10 Republicans and eight in 10 Democrats and political independents say they believe such a conflict is coming.

In the face of continuing violence, half -- 52 percent -- of those surveyed said the United States should begin withdrawing forces. One in six favors immediate withdrawal of all troops, however, while about one-third prefer a more gradual return.

The survey also found growing doubt that the Bush administration has a strategy in Iraq. Two-thirds of those interviewed said they do not think the president has a clear plan for handling the Iraq situation, the highest level of doubt recorded since the question was first asked three years ago. But an even larger share -- 70 percent -- questions whether Democrats in Congress have a plan for dealing with Iraq, suggesting Americans see neither party as offering a coherent exit strategy.

The survey highlights how support for the war in Iraq dissolved since the first months after the U.S. invasion. At the end of 2003, nearly six in 10 -- 59 percent -- said the conflict was worth the cost; today, 42 percent share that view. In the past nine months, the proportion in Post-ABC polls who say the United States should begin withdrawing its troops has increased from 38 percent to a 52 percent majority.

Recent U.S. reversals in Iraq have not dramatically reduced overall support for President Bush, in contrast to some other national polls. His overall job approval rating stood at 41 percent, essentially unchanged from January. Nearly six in 10 disapproved of his job performance, the 11th consecutive survey since last April in which at least half the country has been critical of Bush's leadership.

In only one area -- terrorism -- does more than half of the public see Bush positively, and even here 46 percent disapprove while 52 percent approve. On every other issue tested in the poll -- including the economy, international affairs and health care -- Bush received negative marks.

Americans also expressed disappointment with Congress, which is now controlled by Republicans. Slightly more than a third -- 36 percent -- said they approve of the way Congress is doing its job, down seven percentage points in the past five weeks and the lowest marks for the legislative branch since October 1997.

But the survey showed Democrats slipping also. Asked which party they trust to deal with the country's biggest problems, 42 percent said the Democratic Party and 40 percent said the GOP. Barely five weeks ago, Democrats held a 14-point advantage.

Americans continue to fault the administration's performance in Iraq. Well under half -- 40 percent -- think Bush is doing a good job there, unchanged from late January but still down six points from December. Nearly six in 10 -- 57 percent -- said the war was not worth fighting, marking the 12th consecutive poll since December 2004 in which a majority said invading Iraq was a mistake.

In question after question, the new survey reflected a sharp decline in optimism, perhaps sparked by the sectarian violence that has flared in Iraq after the bombings of a revered Shiite mosque two weeks ago. Since then, deadly confrontations have occurred between Shiites and Sunnis, who are a minority in Iraq but were favored under Saddam Hussein's regime.

The poll found that 56 percent think the United States is not making significant progress toward restoring civil order in Iraq, while 43 percent think that stability is being reestablished -- a 17-point drop in optimism since December and the most pessimistic reading on this question since it was first asked in June 2004.

The nation is split down the middle over whether the United States is moving ahead toward establishing a democratic government in Iraq. About half, 49 percent, say the United States is making progress on the political front, with 48 percent saying the nation and its allies are not gaining ground. Shortly after the December elections, almost two in three Americans said the country was making significant progress toward democracy.

Over the weekend, pressure mounted on Prime Minister Ibrahim al-Jafari to give up his bid for a new term, a move that would add to the political turmoil engulfing Iraq.

Although news from Iraq has not been good, the survey suggests Bush has been helped somewhat by improving perceptions of the U.S. economy. Forty-three percent believe the economy is either excellent or good, up from 35 percent four months ago. And nearly half -- 48 percent -- of the country approve of the way Bush is handling the economy, 12 points higher than in November. Still, slightly more than half (51 percent) disapprove.

Bush's standing in other areas is mixed as well. More than six in 10 disapprove of the way he handled Hurricane Katrina, a nine-point increase since early September. A growing majority (58 percent) also disapproves of the way he is dealing with the prescription drug issue. But his overall approval ratings on terrorism (52 percent), health care (38 percent), international affairs (44 percent) and ethics in government (40 percent) remain basically unchanged from recent Post-ABC polls.

Perceptions of Democrats, who have struggled to take advantage of Bush's lack of popularity, declined on several measures. In late January, Democrats held a clear advantage over Republicans -- 55 to 37 percent -- on which party could best handle the economy. In the new poll, Democrats still led, but by 49 to 40 percent.

The survey found a similar shift on Iraq. In January, Democrats had an advantage of 47 to 40 percent on which party could better handle the situation there, but the new poll found Americans evenly divided -- 42 percent on each side -- on that question.

A total of 1,000 randomly selected Americans were interviewed March 2 to 5. The margin of sampling error for the overall results is plus or minus three percentage points.

Assistant polling director Claudia Deane and staff writer Dan Balz contributed to this report.

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