President Thabo Mbeki has been caught off-guard by the "really early" start of the campaign by his deputy, Jacob Zuma, to succeed him as president in four years.

This is the opinion of political journalist and author William Mervin Gumede, whose recently published book Thabo Mbeki and the Battle for the Soul of the ANC has created major interest and is already on its third impression, as well as topping the non-fictional best-seller list of a major South African book chain.

Speaking at a Cape Town Press Club lunch yesterday, Gumede said he did not believe claims that Mbeki would attempt to seek a third term as president - a move that would require a constitutional amendment Ramaphosa is still a 'top contender'.

"I think he will leave," he said.

However, Mbeki wanted to have a say in who would succeed him as president, and this was proving "much more difficult" than the president had thought.

Mbeki had been caught off-guard by Zuma's early campaign start, and his tendency was now to block Zuma.

However, the president was facing a dilemma as his apparent one-time favourite, Foreign Affairs Minister Nkosazana Dlamini-Zuma, was apparently not considered sufficiently politically sophisticated.

"I think right now he (Mbeki) doesn't know who to put his money on," Gumede said.

Business tycoon and former ANC secretary-general Cyril Ramaphosa was still a "top contender" within the ANC, he added, and was one of the elements in a "very, very important" psychological transition that the ANC was battling to come to terms with.

"For the first time, the ANC as a liberation movement is having to deal with people who have power outside the ANC and also within it - people who have power separate from political power."

It was part of Mbeki's political genius that he could keep the ANC's internal fights out of the public eye, although these did occasionally "bubble up" for public scrutiny.

Gumede said a central thesis of his book was that there was "quite a bit" of self-censorship within the ANC, and that this was a major concern.

"We're not going to build this democracy if everyone is scared to speak out."

He had had to be "really persuasive" to get several of the people he had spoken to for the book even to allow him to list their names as having been interviewed.

There was now much less space for open debate within the ANC than previously, he argued.

"That is part of the ANC that has been lost, or, if not lost, at least significantly eroded."

An example was the failure of senior ANC figures to challenge Mbeki about his controversial views on HIV/Aids between 1997 and 2002.

It was only when medical scientist William Makgoba, then president of the Medical Research Council and now vice-chancellor of the University of Natal, had spoken out and told the president to leave the issue to medical specialists, that Mbeki had been successfully challenged on the subject.

If influential members of the ANC had criticised the president, "it would have been a different story", Gumede said.

"If they'd taken him on head-on, millions of people would not have died."

Gumede said Mbeki had not responded personally to the book, although he had on one occasion answered an agency journalist who had asked him about it during a media conference about the Ivory Coast crisis.

Mbeki had said that the book was "fanciful" and had pointed to his record as a rebuttal.

The presidency had called the book "dark" and some elements in this office had apparently urged Mbeki to allow a "very hard-hitting" response.

But others had told Gumede that the book had been "very useful" to them, and had apparently been suggesting that the president should not respond too harshly.

Gumede said he understood that Mbeki would comment personally just before the ANC's special conference next month.

With acknowledgements to John Yeld and the Cape Argus.