President Bush received the highest disapproval rating of his presidency earlier this month, with 58 percent of respondents saying they don't approve of the way he is handling his job.
According to a USA Today/CNN/Gallup Poll, conducted from Sept. 16 to Sept. 18, Bush's disapproval rating moved 2 points above the previous August high of 56 percent.
Casey Dominguez, professor of political science at the University of San Diego, said the public is reacting to both Bush's handling of the federal response to Hurricane Katrina and the ongoing war in Iraq.
"Forty percent is real low, historically speaking," she said, adding that Bush's numbers could rise if attention shifts to new issues.
But opponents of the administration's Iraq policy are working to keep that issue front and center.
At least 100,000 anti-war protestors gathered in Washington, D.C., on Saturday to voice their opposition to the Iraq war.
William Leuchtenburg, professor emeritus of history at UNC, said the Washington protest probably will not have a lasting effect on public opinion or approval ratings, unless it causes additional demonstrations. "It is important only if it is a harbinger of more and larger protests to come."
The protest in Washington might have at least some constraining effect on the White House, said Michael Hunt, professor of history at UNC.
Though public demonstrations against the Iraq war have not approached the scale of those during Vietnam, they still serve as a reminder to political leaders, he said.