President Bush has reversed the downward drift in public support for war with Iraq despite widespread fears that the conflict would continue for many months and produce large numbers of U.S. casualties, according to a Washington Post-ABC News poll.

After the president's State of the Union speech on Tuesday in which he laid out the case for a U.S.-led invasion, the survey found that 66 percent of Americans favor taking military action against Iraq, up from 57 percent two weeks ago and the most support for war since mid-September.

Slightly more than six in 10 Americans also approve of the way Bush is handling the situation in Iraq; two weeks ago, half the country endorsed the job that the president was doing. Bush's overall job approval rating stands at 62 percent, up slightly from mid-January.

And for the first time in Post-ABC News surveys, about half of all Americans say the United States should take military action even without the endorsement of the United Nations.

The survey is based on telephone interviews conducted Thursday through yesterday with 855 randomly selected adults. Margin of sampling error is plus or minus 4 percentage points.

Support for war is growing even though most Americans are realistic about the consequences. Two-thirds of those interviewed said they expect "significant" numbers of U.S. military casualties if the United States attacks Iraq. Less than one in five -- 19 percent -- believe the conflict would be over in a "few weeks," while 32 percent say it would probably last several months, and 45 percent predict that it could continue for a year or more.

Taken together, nearly four in 10 respondents expected the conflict would be relatively long and relatively bloody. But even among those who most fear a high-cost war, a narrow majority -- 52 percent -- still favors taking military action against Iraq.

Fifty-four percent of the country said the administration has presented enough evidence to demonstrate the need for military force, up from 48 percent in mid-January. Less than half worry that Bush is moving too fast to war, down slightly from two weeks ago.

But most Americans -- 57 percent -- would like to see Bush present more evidence before using force. Two thirds said the United States should be prepared to offer its own hard evidence to the United Nations to support an attack. And 52 percent said circumstantial evidence alone isn't enough to justify taking military action against Iraq.

The administration will have another opportunity to sway public opinion at home and abroad on Wednesday, when Secretary of State Colin L. Powell is to present fresh evidence to the U.N. Security Council that Iraqi President Saddam Hussein is hiding weapons of mass destruction.

The poll suggests that the country has not reached consensus on key questions regarding a possible invasion.

Half of those interviewed agreed with Bush that the United States should give U.N. weapons inspectors only a few more weeks to search for chemical, biological and nuclear weapons in Iraq, while nearly as many are willing to give them a few months or more before going to war.

About half the country is concerned that a war with Iraq would take money way from needed programs, but just as many are not concerned about the war's cost.

Opinions regarding the possible invasion also continue to have a strongly partisan cast, with Republicans much more likely to support Bush's aggressive stance, which most Democrats oppose.