Obama had a white American mother and a black Kenyan father. It is one irony of the controversy over Wright that unity over race was one of the strongest elements of Obama's campaign, said Wallis, who said he was politically neutral.
"It would be the most tragic thing if the black leader most able to help America turn the page on race would be dragged down by a show of anger in the black community," Wallis said.
Wright spoke from a black church tradition spanning several denominations and also some mosques, which emphasises a fight against injustice in preaching and draws inspiration from Old Testament prophets like Hosea, scholars and pastors said.
The Rev Martin Luther King stood in that tradition and many of his speeches made people uncomfortable, they noted, though some of Wright's comments appeared to directly echo statements made by civil rights leader Malcolm X.
"What he is essentially doing is affirming a people who have historically been humiliated," said Aaron Parker, pastor of the Zion Hill Baptist Church, an African-American church in Atlanta.
One recent example of the tradition was a sermon by civil rights leader and preacher Joseph Lowery at the funeral of King's widow, Coretta Scott King, in 2006.
With Bush standing behind him, Lowery compared the president's pursuit of war in Iraq with what he said was an inadequate policy on race and poverty in the United States.
"We know now there were no weapons of mass destruction over there. But Coretta knew and we know that there are weapons misdirection right down here," Lowery said. He was later criticised for being disrespectful.
Estimates of how many black churches use this style of preaching vary but it might represent 25 per cent, said Harry Jackson, pastor of the 3,000-member Hope Christian Church, a multiracial but mainly black church in Washington DC.
Many blacks would tolerate the views expressed by Wright even if they did not agree with them, said Jackson, co-author of a book about personal faith and public policy.
But many black Christians who had chosen churches that eschewed the kind of language used by Wright would be shocked that Obama had stayed in the church so long and would question his judgment, said Jackson, who is neutral in the election.
"A lot of people are going to feel misled. It's problematic and it's not easy to explain. It looks very hypocritical," he said.
