Jacob Zuma has been re-elected as leader of South Africa's governing African National Congress.He received an overwhelming majority of votes cast by some 4,000 delegates at the party's Mangaung conference.Mr Zuma had been favourite to secure the leadership after he was challenged for the top job by his deputy Kgalema Motlanthe.Mr Motlanthe has been replaced as deputy president by anti-apartheid veteran Cyril Ramaphosa.The ANC, which has governed South Africa since white minority rule ended in 1994, is widely expected to win nationwide elections due in 2014.This means Mr Zuma is likely to remain president until 2019.Meanwhile, four white men have appeared in court accused of being part of a right-wing extremist plot to bomb the ANC conference.The men were arrested on Monday in raids across the country and reportedly face treason and terrorism charges.Flagging supportThere were deafening sounds of vuvuzelas, huge applause and singing as the results of the election were announced, the BBC's Milton Nkosi reports from the conference.Mr Zuma won 2,986 votes out of the 3,977 cast - making it a decisive victory against his rival, Kgalema Motlanthe.Mr Motlanthe ended months of speculation by announcing his decision to run against Mr Zuma for the leadership and declining to stand again as deputy leader.It is not clear where this result leaves his political career.But it marks a return to the political frontline for Mr Ramaphosa, a veteran of the anti-apartheid movement and more recently a successful businessman.His decision to run as Mr Zuma's deputy has been seen by analysts as a way of shoring up the president's flagging support.Mr Zuma has been accused of failing to reduce poverty or tackle corruption within the ANC and government, while in August there was widespread shock when police shot dead 34 striking miners in the most deadly police action since the end of apartheid.Some of President Zuma's supporters began celebrating his win, even before the results were in.