Members of South Africa's governing party are to choose who will lead them for the next five years.
The vote will take place at the ANC's national conference, which begins today.
Their choice could determine who will become President of South Africa in less than two years' time.
In spite of a decade of economic growth in South Africa, President Thabo Mbeki has become increasingly unpopular within sections of his own party.
The ANC Deputy President, Jacob Zuma, is facing corruption charges but is favourite to become the new ANC leader.
Nelson Mandela said divisions within the ANC are saddening. The comments by Mr Mandela are the first he has made publicly on the ANC leadership crisis.
