Democrat Barack Obama is calling accusations by Hillary Rodham Clinton "ludicrous."
Clinton suggested Sunday that Obama's campaign had injected racial tension into the campaign. She told NBC's "Meet the Press" Obama had distorted her comments about Martin Luther King's role in the civil rights movement.
Clinton was earlier quoted as saying King's dream of racial equality was realized only when President Lyndon Johnson signed the Civil Rights Act of 1964.
Later, the Clinton campaign scrambled to explain comments by one of its top black supporters, BET founder Bob Johnson, that seemed to raise the issue of Obama's admitted teenage drug use.
During an event with Clinton in South Carolina, Johnson referred to when "Barack Obama was doing something in the neighborhood." Johnson said, "I won't say what he was doing, but he said it in his book."
The Clinton campaign later released a statement in which Johnson said his comments referred to Obama's years as a community organizer in Chicago.