Philadelphia: Democratic presidential candidate Barack Obama on Tuesday criticized his preacher's racially charged sermons but said he could not disown him in a speech urging Americans to move past their "racial stalemate."

While condemning the remarks of his controversial pastor on Tuesday Obama took several steps to explain why Rev. Jeremiah Wright’s incendiary rhetoric is still valid.

Going to great lengths and several times repeating his reason for his continued association to Wright and his membership at Trinity United Church of Christ in Chicago, Obama said the pastor introduced him to his Christian faith and continues to perform God’s work on earth.

“As imperfect as he may be, he has been like family to me. … I can no more disown him than I can disown the black community. I can no more disown him than I can my white grandmother,” Obama told an audience at the Constitution Center in Philadelphia.

Threading a tough needle

Obama is seeking to return his campaign to the place it was until about a week ago, before his image was tarnished by the details of his relationship to Wright, who has been Obama’s spiritual adviser for 20 years.

Obama has tried to mold himself as a transcendent American political figure not viewed uniquely as an African-American running for the presidency but rather a candidate who is African-American and uniting the country behind him.

In a speech billed as one on race, politics and unifying America, Obama described his interracial background — a white American mother and black African father — as well as his wife’s ancestral history of slavery.

He credited the United States for allowing the freedom that enabled him to enjoy such a mix.

“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.It 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,” he said.

Defining the freedoms that this nation’s inhabitants enjoy, Obama said he did not excuse some of the anti-American statements made by the pastor, though he acknowledged that he knew Wright to be a fierce and vocal critic of US policy.

Obama had worked late into the night on Sunday drafting his speech, reports say.

Rev. Jeremiah Wright, served as the pastor at the Chicago church where the Illinois senator was a member for 20 years.

In sermons widely circulated in the media, Wright has called the Sept. 11, 2001, attacks retribution for US foreign policy, cited the US government as the source of the AIDS virus, and railed against a racist America.

Wright recently retired from his role as pastor of Trinity United Church of Christ on Chicago's South Side.

Obama has denounced Wright's comments and the pastor stepped down from his role as spiritual adviser to the Obama campaign. Obama likened him to an "old uncle."

Wright performed the marriage ceremony for Obama and his wife and baptized their two children.