'Impossible in South Africa'

However, if the ANC achieves a two-thirds majority in the polls they would be able to change the constitution, and provide Zuma with immunity.

But he said: "[It is] Impossible in the South African setting."

"There is no president, whether he wins with a two thirds majority, who can then stand up and say 'I am now cancelling these charges'".

"We are treating our constitutional democracy so well that [it can be said of] no citizen of this country ... that because he or she holds certain positions cannot be tried."

Zuma says that the charges against him are politically motivated.

Zuma reaffirmed past comments that if he were to be convicted the ANC has many leaders that could replace him.

"We are the only organisation here with a big collective of leadership from which you could produce a president," he said.

COPE challenge

A faction broke away from the ANC last year and the Congress of the People (COPE), the resulting political party, is now expected to win second place in the elections.

However, Zuma said that he did not expect COPE to take a significant number of votes from the ANC.

"Why should they get it? What is it that they are offering to the people of the country?" he said.

"This is an imagined threat to the ANC."

"COPE emerged in 2008 ... less than a year to the elections. Is itry common that you can establish a party in that short period of time and be in a position to prepare for elections - such serious elections like the ones that are coming in a matter of months?"