Using his own DNA as a blueprint of a post-race America, Democratic presidential candidate Barack Obama yesterday denounced and defended his controversial former pastor, the Rev. Jeremiah Wright.

Speaking in Philadelphia, Obama said he understood the love and failure of both black and white races because he was of both. The son of a black man from Kenya and a white woman from Kansas — and who was raised in Hawai'i — used his white grandmother as personal testimony to that effect.

Some commentators called his speech yesterday one of the best they've heard on race in America. But whether the Illinois senator was successful in calming a political storm depends on whether voters and commentators focus on a broader context Obama tried to draw.

If Obama was unable to move the primary focus away from his relationship with Wright, the controversial and recently retired pastor of the Trinity United Church of Christ on Chicago's South Side, the speech may not turn out to be as effective as many of Obama's supporters had hoped.

Speaking in a state that will be the next presidential battleground with New York Sen. Hillary Rodham Clinton on April 22, Obama said the United States stands at a crossroads between continuing to treat racial differences as "spectacle" and "fodder for the nightly news," or as a starting point toward a "more perfect union" as envisioned by its Founders in Philadelphia over two centuries ago.

His mixed-race heritage "hasn't made me the most conventional candidate," Obama said, but he argued that his is "a story that has seared into my genetic makeup the idea that this nation is more than the sum of its parts — that out of many, we are truly one."

Obama, who was born in Hawai'i and graduated from Punahou School, has often spoken fondly of his maternal grandmother, Madelyn Dunham, who helped raise him. He calls Dunham "Toot," a variation of "Tutu," which many people call their grandmothers in Hawai'i.

Obama usually visits Dunham, a former bank vice president, and his sister, Maya Soetoro-Ng, a history teacher at La Pietra Hawai'i School for Girls, at Christmas.

Dunham, reached at her Beretania Street home last night, said she was not giving interviews.

Soetoro-Ng said she had not seen her brother's speech because she woke up just in time to get her children to school and make it to work.

"I'm glad that people are getting a chance to hear from him directly and that he is offering an explanation that is richer and fuller than that which has been afforded him in recent days," she said.

Soetoro-Ng has said previously that Obama's experiences growing up in Hawai'i have helped him connect with people of different racial and ethnic backgrounds. Obama has spoken of Hawai'i as a place that has embraced racial harmony but said he is not immune to issues of race and social class.

But Obama did not mention his Hawai'i experiences in his speech yesterday on race other than the references to his parents and grandparents.

Brian Schatz, a local Obama volunteer and former Makiki state representative, said Obama showed leadership by rising above the daily back and forth on race and gender and giving a substantive speech.

"I have never heard a major political candidate be so frank about what people say behind closed doors about other ethnic groups," Schatz said.

'THE BLACK EXPERIENCE'

In his 36-minute speech, Obama defended the rhetorical traditions of the black church, which he said "contains in full the kindness and cruelty, the fierce intelligence and the shocking ignorance, the struggles and successes, the love and yes, the bitterness and bias that make up the black experience in America."

He said that Wright's biggest failing was in not recognizing the progress that has put Obama on the precipice of the Democrats' presidential nomination. But, Obama said, discrimination, segregation and economic disparity "is the reality in which Rev. Wright and other African-Americans of his generation grew up."

"I can no more disown him than I can disown the black community," Obama said. "I can no more disown him than I can my white grandmother — a woman who helped raise me, a woman who sacrificed again and again for me, a woman who loves me as much as she loves anything in this world, but a woman who once confessed her fear of black men who passed her by on the street, and who on more than one occasion has uttered racial or ethnic stereotypes that made me cringe."

Obama said many poor and middle-class whites share the same concerns as black Americans, and that he stood uniquely among both.

"I have brothers, sisters, nieces, nephews, uncles and cousins of every race and every hue, scattered across three continents, and for as long as I live, I will never forget that in no other country on Earth is my story even possible," Obama said.

Kathleen Hall Jamieson, one of the nation's foremost experts on political communication, said the rhetorical connection between Wright and Obama's grandmother was "a very effective use of the personal as rebuttal."

Ron Walters, a political scientist at the University of Maryland and former adviser to the Rev. Jesse Jackson, agreed.

"That was about Obama saying that he could no more turn away from Rev. Wright for his racial descriptions of life than he could turn away from his white grandmother for her racial descriptions of life — that he disagreed with both but that he was not going to disavow either," Walters said. "A lot of people expected with this speech that Obama would throw the reverend under the bus, or the church under the bus. He did not do that."

But while acknowledging that Wright had made "divisive" and "racially charged" comments, he did not disown his pastor of 20 years. Obama said the remarks were out of context of a minister who had inspired his own faith, and whose church had established a deep tradition of aiding and comforting its community.

A DISTRACTION

In the speech, Obama portrayed arguments over race as a distraction.

"We can accept a politics that breeds division, and conflict, and cynicism," Obama said. "We can tackle race only as spectacle — as we did in the O.J. trial — or in the wake of tragedy, as we did in the aftermath of Katrina — or as fodder for the nightly news. We can play Reverend Wright's sermons on every channel, every day and talk about them from now until the election." If that happens, Obama said, "nothing will change."

A Quinnipiac University poll of Pennsylvania Democrats released yesterday found Clinton leading in Pennsylvania among white voters 61 percent to 33 percent. Black voters supported Obama 76 percent to 18 percent. Overall, Clinton was leading 53 percent to 41 percent.