Support for military action in Iraq is falling faster than the autumn leaves as Americans express concerns about casualties and renewed doubts about whether there is a clear case for war, according to a new national survey by the Pew Research Center for the People & the Press.

A bare majority--55 percent--said they back military strikes in Iraq, down from 62 percent in early October. At the same time, the proportion expressing opposition has increased from 28 percent to 34 percent.

For the first time "since the Iraq debate intensified this summer, a majority of Democrats oppose the use of force to remove Saddam Hussein from power," reported Andrew Kohut, director of the Pew Center.

Americans are growing even more unenthusiastic over the prospects of going it alone in Iraq. When asked if the United States should take military action against Saddam Hussein without the support of allies, barely more than one in four--27 percent--said it should, down from 33 percent in mid-September, while 23 percent said they would support such a move only if the allies agreed to take action.

The survey found broad concern about the potential consequences of any military action against Iraq. Leading the list is concern that Hussein will use chemical or biological weapons against U.S. troops, a worry shared by 59 percent of those interviewed.

"Compared with the first Persian Gulf War, many more Americans fear a conflict with Iraq will raise the risk of terrorism in the United States" is a view shared by half of those interviewed in the latest Pew survey, compared with a third of respondents during the Gulf War in January 1991.

Nearly half of those surveyed also worry that strikes against Hussein might spark a war in the Middle East. And more than four in 10 are concerned that Iraq will remain unstable long after Hussein is ousted.

A total of 1,751 adults were interviewed Oct. 17-27 for this survey. Margin of sampling error for the overall results is plus or minus 3 percentage points.

The poll found that support for war has fallen among all major demographic and political groups. A majority of men--59 percent--said they support war, but that was a drop from 68 percent in early October. Fifty percent of the women who were polled back military action, down from 59 percent.

Backing for the war option dropped 6 percentage points among whites, to 59 percent, but has plummeted from 43 percent to 31 percent among blacks in two weeks.

"The falloff in support for military action has been comparable among Democrats and Republicans (nine points and seven points, respectively)," Kohut wrote. "But a majority of Democrats (51 percent) now oppose using force to oust Saddam, while 40 percent favor military action. In early October, Democrats supported military action 49 percent to 43 percent."

Even among conservative Republicans, support has fallen slightly, from 80 percent in early October to 76 percent in the latest survey.

One reason for the drop is that most Americans no longer believe that Bush has made the case against Hussein.

"In September, President Bush made significant progress in explaining his case for military action in Iraq to the American public, but the new poll indicates that, if anything, he has lost ground in this effort since then," Kohut wrote.

According to the poll, Americans are sharply divided over whether Bush has clearly explained the stakes in Iraq, with 48 percent saying he has but 45 percent saying he has not. That's down from September, when a majority thought Bush had presented a convincing case against Hussein. "The perception that Bush is not making a clear case for war has increased among all demographic groups," Kohut reported.

You Pick 'Em

So how's President Bush doing? Hard to tell, from the polls released last week. Over at ABC, their survey found Bush's overall job approval rating at 67 percent, unchanged in the past month. But the latest Pew Center survey pegged the president's job rating at 59 percent, compared to 61 percent in early October. Harris and Newsweek had it at 61 percent, while Fox News/Opinion Dynamics came in at 60 percent. Some of these differences are due to "house effects"--the fact that some polling firms try a little harder to push reluctant respondents to answer the question rather than allowing them to say they "don't know." Most--though not all--suggested that Bush's job standing was continuing its downward drift.

Crime and Punishment

Most Americans favor the death penalty for both suspects in the serial sniper murders, according to a survey by Harris Interactive for Time/CNN. If he is found guilty, seven in 10 said they favor death for John Allen Muhammad, 41, while one in four said he should be sentenced to life in prison. Slightly more than half--51 percent--said John Lee Malvo, 17, should also be executed if convicted, while 43 percent said they favor a life sentence for the juvenile.

Richard Morin is director of polling for The Washington Post.