Democratic presidential hopeful Barack Obama said Tuesday that the Bush administration has done nothing to defuse a "quiet riot" among blacks that threatens to erupt just as riots in Los Angeles did 15 years ago.

The first-term senator said that with black people from New Orleans and the Gulf Coast still displaced 20 months after Hurricane Katrina, frustration and resentments are building.

"This administration was colorblind in its incompetence," Obama said at a conference of black clergy, "but the poverty and the hopelessness was there long before the hurricane.

"All the hurricane did was to pull the curtain back for all the world to see," he said.

Obama is bidding to become the first black U.S. president.

Obama's attack on Bush got ovation after ovation from the nearly 8,000 people, particularly when he denounced the Iraq war and noted that he had opposed it from the outset.

Repeatedly, he referred to the riots that erupted in Los Angeles after a jury acquitted four police officers of assault charges in the 1991 beating of Rodney King, a black motorist, after a high-speed chase. Fifty-five people died and 2,000 were injured in several days of riots in the city's black neighborhoods.

"Those 'quiet riots' that take place every day are born from the same place as the fires and the destruction and the police decked out in riot gear and the deaths," Obama said. "They happen when a sense of disconnect settles in and hope dissipates. Despair takes hold and young people all across this country look at the way the world is and believe that things are never going to get any better."

Repeatedly, with evangelical zeal, he raised issues that roused the crowd: increasing the minimum wage and teacher pay, funding for public schools and college financial aid for the poor, ending predatory lending and expediting the reconstruction of New Orleans and the Gulf Coast.

Obama does not regularly focus on racial themes in his standard campaign speeches. He did speak out on black issues in Selma, Alabama, in March, when he told a largely black audience that he was a product of the civil rights movement and lectured blacks for failing to vote in large numbers.

Several ministers at the conference said Obama's message and style plays well among black voters and their spiritual leaders.

The Rev. Robert Abbott, pastor of the Holy Trinity Baptist Church in New York state, said Obama connects with black audiences because of the preacher's style he uses when addressing them.

"The way he sounds, it's like he can reach out and encourage people," Abbott said.