Obama's historic speech: Schoolchildren will listen to this one in the future.

Barack Obama unsparingly criticized his longtime pastor's words while strongly defending the man himself Tuesday in a politically risky speech that appealed to the country to overcome racism and the black anger and white resentment it spawns.

In his most pointed speech of the campaign, Obama confronted the nation's legacy of racial division head on, tackling black grievance, white resentment and the uproar over his former pastor's incendiary statements. Drawing on his half-black, half-white roots as no other presidential hopeful could, Obama urged Americans to break "a racial stalemate we've been stuck in for years.'"

Obama's advisers say the candidate decided on Saturday to make the speech and spent much of Sunday and Monday writing it, finishing shortly before he took the stage. They said Philadelphia was chosen not because it has the highest concentration of blacks in Pennsylvania, the next state to vote on April 22, but because of its historical significance.