WASHINGTON -- Hurricane Katrina has accelerated the erosion in public support for the Iraq war as President Bush's core of supporters dwindles and economic pessimism turns Americans' attention inward.

A new Wall Street Journal/NBC News Poll shows that cutting spending on Iraq is Americans' top choice for financing the recovery from Katrina. Shaken by high gas prices and bracing for further jolts, Americans have turned negative about Mr. Bush across the board -- on handling the economy, foreign policy, and even the war on terrorism.

The president's overall approval has fallen to a record-low for Mr. Bush of 40%, reflecting a shrunken core of base supporters. That promises to have repercussions for his domestic agenda on issues like Social Security, taxes and immigration, and leaves Mr. Bush with a steeper challenge on his most significant second-term priority: using American power and resources to transform Iraq and the broader Middle East.

A plurality of Americans has favored reducing troop levels in Iraq for most of the year. Now, 55% favor bringing soldiers home, while just 36% back Mr. Bush's position that current levels should be maintained to help secure peace and stability.

"His standing to prosecute that case has been made more difficult," says Republican pollster Bill McInturff, who helps conduct the Journal/NBC Poll. Adds Democratic counterpart Peter Hart: It's "going to be very hard to just move straight forward" on Iraq.

To be sure, the survey contains some bright spots for Mr. Bush. Federal appeals court Judge John Roberts, his nominee to succeed the late William Rehnquist as chief justice of the Supreme Court, has drawn respectable support and little intense opposition. Some 38% say they support Judge Roberts for that post, while just 20% oppose him and 41% don't know enough to say.

Nearly half of U.S. adults say President Bush has done a poor job in handling the Hurricane Katrina relief efforts, according to a recent Harris poll. And almost half expect the hurricane will have a great impact on the U.S. economy.

And while Senate Democrats press Judge Roberts in Judiciary Committee hearings to state his views on key issues, 57% of Americans say the nominee shouldn't be required to spell them out since those issues may come before the court. Democrats enjoy firmer support in public opinion for their demand for more documents about Judge Roberts's previous government service; 41% say the White House should make additional documents public, outpacing the 31% who say Democrats already have enough information.

Yet the poll's findings about Americans' priorities show the work facing Mr. Bush, who is scheduled to deliver a nationally televised address tonight on the recovery from Katrina. Some 60% say rebuilding the Gulf Coast should be a higher national priority than establishing democracy in Iraq; 5% say Iraq, while 34% say the two are equally important.

The White House says the administration can handle both at once, but by 51%-37% Americans say the Iraq war wasn't worth its human and financial costs.

The proportion of Republicans disapproving of Mr. Bush's job performance has doubled to 15% from 7% in January, with pronounced defections among moderates within Mr. Bush's party.

Katrina has contributed to that decline in support. By a 58%-38% margin, Americans say they are dissatisfied with the Bush administration's response to the catastrophe. Reflecting the absence of the traditional rally behind the commander in chief during national emergencies, just 48% approve of the president's handling of the matter; 80% approved of how he handled the aftermath of the Sept. 11, 2001, terrorist attacks, while 64% backed the actions of his father, President George H.W. Bush, following Hurricane Andrew in 1992. The survey of 1,013 adults, conducted Sept. 9-12, has a margin for error of 3.1 percentage points.

In particular, Katrina appears to have shaken public regard on two attributes that sustained Mr. Bush through earlier political challenges. The public now splits evenly, 41%-41%, on assessments of Mr. Bush's ability to handle a crisis; at the outset of his second term in January, he received positive marks for crisis-management ability by a 56%-28% margin. A bare 43%-40% plurality rates him positively for having "strong leadership qualities," down from 52%-30% in January.

The crisis along the Gulf Coast may have also damaged the long-term effort by Mr. Bush's strategists to expand Republican support among members of minority groups. Fully 70% of African-Americans say the Bush administration would have reacted to Katrina with greater urgency had the affected areas been mostly white suburbs rather than mostly black inner-city neighborhoods. Nearly seven in 10 whites reject that assertion.

Hispanics are divided evenly on the question. But the president's overall rating among Hispanics, who were split on his job performance in January, is now negative by a two-to-one margin.

Mr. Bush's signature domestic priority, overhauling the Social Security system with private investment accounts, was already in political trouble before the hurricane. Assessments of the administration's handling of Social Security -- 28% say they are satisfied while 60% aren't -- are more negative than assessments of how it handled the response to Katrina.

Beyond Social Security, the domestic political landscape has been buffeted in a way that complicates challenges facing the White House and Republicans in the 2006 midterm elections. Following the gas-price spikes immediately after the hurricane, six in 10 Americans now expect pump prices to continue rising.

In fact, the public now ranks gas prices as the country's top economic issue. Just 6% assign top importance to federal taxes, the issue that Mr. Bush and Republicans planned to elevate next year through a yet-unspecified overhaul of the tax system.

Of particular concern to lawmakers facing voters next year, Americans have turned pessimistic on the outlook for the economy. Some 49% expect the economy to get worse over the next 12 months, triple the 16% who expect it to improve. In January, those numbers were essentially reversed.

At the same time, Katrina may have left the public feeling slightly more nervous about security at home. Fully 75% of Americans now say the U.S. isn't adequately prepared for a nuclear, biological or chemical attack, up from 66% who expressed that concern in 2002.

The net effect may be increased pressure on members of the Republican majority to strike an independent course on a range of issues, resisting appeals for party discipline that have been effective for most of Mr. Bush's presidency. Those pressures will be greatest in the Northeast and Midwest, where Mr. Bush's approval rating stands at 32% and 36%, respectively.

"All these [results] suggest unstable days ahead in the Republican caucus," says Mr. McInturff, whose firm advises many Republican lawmakers.

Write to John Harwood at john.harwood@wsj.com

Commentary: