This from the latest Pew Research Report:
The American public is highly critical of President Bush’s handling of Hurricane Katrina relief efforts. Two-in-three Americans (67%) believe he could have done more to speed up relief efforts, while just 28% think he did all he could to get them going quickly. At the same time, Bush’s overall job approval rating has slipped to 40% and his disapproval rating has climbed to 52%, among the highest for his presidency. Uncharacteristically, the president’s ratings have slipped most among his core constituents – Republicans and conservatives.
The disaster has triggered a major shift in public priorities. For the first time since the 9/11 terror attacks, a majority of American say it is more important for the president to focus on domestic policy than the war on terrorism. And the poll finds that Katrina has had a profound psychological impact on the public. Americans are depressed, angry and very worried about the economic consequences of the disaster. Fully 58% of respondents say they have felt depressed because of what’s happened in areas affected by the storm. In recent years, this percentage is only surpassed by the 71% that reported feeling depressed in a survey taken just days after the Sept. 11 attacks.
The last sentence of the first paragraph is the most significant. Bush's approval rating has always been based on keeping the overwhelming support of his base. If that goes, he's in real trouble.