Pietermaritzburg - Some ANC leaders are bitter and a toxic influence on the party, ANC presidential hopeful Nkosazana Dlamini-Zuma said on Friday evening."You should not have vengeance when you are a leader, but you must talk things over so you lead with a clear mind," she said, delivering the Nelson Mandela Lecture to a packed Pietermaritzburg City Hall ahead of the Mandela Day Marathon on Sunday.She referred to ANC members who took their grievances to the media, instead of raising their concerns with the party’s structures."Why be so bitter until we kill each other, like it’s happening currently?" she asked.Dlamini-Zuma said ANC leaders, like former president Nelson Mandela, who spent 27 years in jail, were not bitter towards whites when they were released.“You can't use personal vendetta to destroy the organisation,” she warned.Leaders had to have integrity and be dependable.Addressing the question of who would succeed her ex-husband, President Jacob Zuma, she said ANC leaders were elected democratically. She called for the ANC to remain united after its elective conference in December."Where do some leaders get that when contesting positions the ANC would be divided?" she asked.ANC members should follow and respect whoever was victorious after the conference.“If you want to be a leader, be prepared to be led. Branches will choose. We can't please every faction.”The ANC is currently divided between supporting Dlamini-Zuma and the party’s deputy president Cyril Ramaphosa to become its next president.She said the ANC had to win the 2019 local government elections, irrespective of who was chosen to lead.Dlamini-Zuma suggested that radical economic transformation would be easy.“Blacks and whites must be happy about radical economic transformation because it will bring investors and create job opportunities for the youth.”White monopoly capital had to be dismantled so others could play a role in the economy."We are not chasing them (whites) away from the country. We must also get land to build houses and our industries. All this needs money. Money is in the banks. More banks should be created to help us," she said.The Democratic Alliance would not transform the economy for the benefit of blacks, but the ANC would, she said.