Many prominent African-Americans, including Rep. James Clyburn, D-S.C., and Democratic political strategist Donna Brazile, have criticized comments by Clinton, her husband Bill Clinton and her aides portraying Obama's message of hope and unity, which draws heavily on the civil rights movement, as unrealistic.

It is not Obama's message, but his ability to follow through that is in question, Clinton said Sunday on NBC's "Meet the Press."

"I have the greatest regard for rhetoric and particularly the ability that Senator Obama has to, you know, lift our sights and our hearts with his oratory," she said. "But I think it is fair to point out that he has not had a record of actually producing positive change. Translating those words into action is something that is the slow, hard, ... and I think that people deserve to ask themselves questions about that contrast."