By Mark Felsenthal
JOHANNESBURG (Reuters) - President Barack Obama will challenge Africans to renew efforts to expand economic growth and democratic government in a speech Sunday, invoking the legacies of Nelson Mandela and the U.S. civil rights movement in overcoming obstacles to achieve change.
"There's been progress that nobody could have imagined in terms of a freer, more equal democratic society here in South Africa, and in many parts of the continent," deputy national security adviser Ben Rhodes told reporters traveling with the president.
But despite those changes, millions still live in extreme poverty, some African governments suppress democratic rights, and there are still children dying of preventable diseases, Rhodes said.
"It's not as if the work was completed here in South Africa or anywhere else in the world simply with the current status quo," he said.
The president is setting the stage for the key address of his eight-day Africa trip by traveling to Robben Island, where Mandela was jailed for 18 of his 27 years in prison, and by delivering the speech at the University of Cape Town, where Robert F. Kennedy gave the anti-apartheid movement heart with his 1966 "Day of Affirmation" speech.
Obama has sought to make his visit, which many Africans felt was long overdue, an extended showcase for U.S-African trade and commercial ties. But those themes have been to some extent overshadowed by concerns over the fast failing health of the 94-year old Mandela.
The U.S. president, who has been greeted by cheering crowds, but also by protesters in some places, has talked about the importance of stable institutions and Africa's economic potential at every stop. Even so, much of the focus on his visit to South Africa has centered on whether he would encounter Mandela, who is in critical condition in hospital due to a lung infection.
Obama observed the wishes of Mandela's family on Saturday, visiting with them but not Mandela himself. He offered the family words of comfort and praised the retired statesman as one of history's greatest figures.
Mandela was elected president of a multiracial South Africa in 1994, four years after being released from prison. Kennedy's 1966 speech called on young people to continue to press for freedom from oppression, whether it came from apartheid or the denial of civil rights to U.S. blacks, and said each person who stood up against injustice sent forth "a tiny ripple of hope."
Obama is to say that despite the huge changes that ensued since Kennedy gave that speech and over Mandela's lifetime, Africa has big challenges ahead. He talk to his young audience of their responsibility as a new generation to improve economic growth, democratic institutions, and social stability, Rhodes said.
The president winds up his Africa journey with a stop in Tanzania on Monday and Tuesday.
(Editing by Eric Walsh)