Democratic Sen. Barack Obama, trying to quell a political firestorm that has roiled his presidential campaign, strongly denounced his former pastor on Tuesday and called his racially charged comments "appalling."

The controversy over the Rev. Jeremiah Wright has been a major stumbling block for the Illinois senator, who is leading New York Sen. Hillary Clinton in the state-by-state contest for the party's nomination for the November election.

Obama was forced to address the issue after Wright spoke on Monday at the National Press Club in Washington, where he repeated earlier suggestions that the United States deserved some blame for the September 11 attacks and that the government had had a hand in spreading AIDS to blacks.

"I want to be very clear that, moving forward, Rev. Wright does not speak for me, he does not speak for our campaign," Obama told reporters as he campaigned for the North Carolina vote against Clinton next Tuesday.

"I cannot prevent him from continuing to make these outrageous remarks, but what I do want him to be very clear about...is that when I say I find these comments appalling, I mean it. It contradicts everything that I'm about and who I am."

Wright's comments have undercut the campaign of Obama, the son of a white mother and a black father who has based his presidential candidacy on a promise to unite the country after years of sharp political and racial divisions.

Wright had also questioned Obama's honesty, saying he had been pandering to voters when he earlier denounced the pastor's words. "If Senator Obama did not say what he said, he would never get elected," Wright said.

ENOUGH

Obama, unsmiling and choosing his words carefully, said: "At a certain point if what somebody says contradicts what you believe so fundamentally and then he questions whether or not you believe it - in front of the National Press Club - then that's enough.

"That's a show of disrespect to me. It is also, I think, an insult to what we've been trying to do in this campaign," he added. "Whatever relationship I had with Reverend Wright has changed as a consequence of this."

Wright, asked on Monday about a speech in which he asserted the September 11 attacks were retaliation for U.S. foreign policy, said: "You cannot do terrorism on other people and not expect it to come back to you."

Asked about another sermon in which he suggested the U.S. government created the AIDS virus to kill black people, Wright said: "Based on what has happened to Africans in this country, I believe our government is capable of doing anything."

Wright, who presided over Obama's wedding and baptized his children, is now semi-retired from Chicago's Trinity United Church of Christ.

"The person that I saw yesterday was not the person that I met 20 years ago," Obama said. "His comments were not only divisive and destructive but I believe that they end up giving comfort to those who prey on hate."

Obama said he liked the church's new pastor and was still a member.

Obama has denounced Wright before and is now adapting his campaign to reintroduce himself to working-class voters who handed wins to Clinton in Ohio and Pennsylvania.

Matthew Wilson, a political scientist at Southern Methodist University in Dallas said the strong comments came late.

"A denunciation at this stage appears to be politically motivated because Rev. Wright didn't say anything yesterday that he hasn't been saying for 30 years," Wilson said.