Obama, who has made little of his race in a so-far bruising run for the White House, was sure to include his personal story in his acceptance address before 75,000 fellow Democrats at a Denver stadium, and millions more watching on television.

But the nominee - the son of a black Kenyan father and a white American mother - was also to talk about the US's many challenges, from health care to international threats, campaign manager David Plouffe said on ABC's Good Morning America news show.

His acceptance of the Democratic nomination comes on the 45th anniversary of the Rev King's August 28, 1963, "I Have a Dream" speech, an exhortation about the frustration of blacks at a time when African Americans in many southern states were denied their voting rights more than 90 years after the federal government guaranteed them that right.