Outgoing African National Congress (ANC) secretary general, Gwede Mantashe, on Thursday said he had mixed emotions as he leaves behind a ''difficult and complex'' office.

He made his comments ahead of the ANC's 54th National Conference in Johannesburg, which begins on Saturday and ends on Wednesday.

''Leaving an office I enjoyed for 10 years is a mixed feeling. It's a very difficult office, very complex ... you absorb blame for everything and not get any credit for anything ... and that's it, we have enjoyed it ... we are coming to an end,'' Mantashe told reporters at conference venue, Nasrec.

Despite disputes around candidate nominations, some of which have ended up in court, Mantashe said the elective conference where President Jacob Zuma's successor as leader of the ruling party will be elected is going ahead as planned.

''We are quite happy that conference will go ahead, it will be successful, it won't collapse ... those who said it will collapse are probably disappointed already,'' said the ANC secretary general.

''It will be the most well organised, most engaging conference. We have the gala dinner tomorrow night and Saturday things will get running.''

The conference, labelled as the most important in the ANC's history, will also see delegates voting for their preferred top six leaders and NEC members. The conference will examine and come up with new policies ahead of the 2019 general elections.

Seven presidential hopefuls have put up their hands to take over from Zuma, but Deputy President Cyril Ramaphosa and former African Union (AU) chairperson Nkosazana Dlamini-Zuma have emerged as front runners for the ANC top job.

Voting for the new ANC president takes place on Sunday.