Large majorities of Americans backed the military invasion, and Bush's approval ratings have jumped since the conflict began.

Despite dogged Iraqi resistance, 74 percent of those asked supported the US decision to go to war, said the Washington Post-ABC News survey taken Thursday night.

That was up slightly from 72 percent a week earlier, on March 20, when the US and British ground offensive was launched in southern Iraq with high hopes of a collapse of Iraqi President Saddam Hussein's regime.

At the same time, 24 percent of those questioned opposed the war, down from 26 percent a week earlier, according to the random telephone survey.

Some 63 percent of those questioned in a separate Newsweek poll taken Thursday and Friday said the United States was right to start military action when it did, while 68 percent approved of Bush's job performance -- up 15 percentage points from two weeks ago.

That figure is still lower than his father's ratings during the 1991 Gulf War, which president George Bush won 86 percent approval.

Nearly half of respondents supported the war even if it were to last more than a year, even though 73 percent said they believed the war would inspire terrorist attacks against Americans.

A Time poll taken Sunday found that 48 percent of people questioned feared the war would draw terrorist attacks on US soil.

Fierce Iraqi resistance, particularly in the cities, appeared to sharply ramp up expectations that US troops will suffer heavier casualties in a longer-haul offensive.

The proportion of respondents expecting a "significant number of additional US casualties" shot up to 82 percent from 37 percent a week ago, the Washington Post-ABC News poll said.

Asked about the costs of the war so far, 58 percent said they were "acceptable" and 34 percent said they were "unacceptable".

When asked to guess how long the war would last, 57 percent said "months", compared with 37 percent a week before, and 23 percent said "weeks", down from 31 percent a week earlier.

Optimists forecasting a war lasting "days" nearly vanished. Their numbers tumbled to two percent from eight percent.

More than 60 percent of people asked in the Newsweek and Time polls said the US media was providing good coverage of the war, though 53 percent told the Newsweek pollsters that US media carried too much Iraqi propaganda.

Only 30 percent said the US media were too controlled by the Department of Defense.

The margins of error were plus or minus five percentage points in the Washington-Post ABC poll of 508 adults; three points in the Newsweek poll of 1,004 adults; and 3.1 points in the Time poll of 1,014 adults.

WAR.WIRE