The results of last weekend's provincial nomination conferences suggest that President Thabo Mbeki's campaign to be re-elected as ANC president has completely run to ground. He received a total of 1407 votes (38,7%) to Jacob Zuma's 2232 (61,3%). Zuma will now enjoy all the momentum going into the conference itself. Presumably the election could still be stolen, but it is very difficult to see how Mbeki could win a free and fair contest at Polokwane.

Only two weeks ago Mbeki's supporters were confidently predicting victory. They told City Press that in "the best-case scenario, Mbeki will win the election by 776 votes. In a worst-case scenario, Mbeki will win by only 203 votes." Now, Mbeki will have difficulty avoiding a landslide defeat, as the opportunistic element rallies behind the ‘inevitable winner'.

This is a small revolution, and it is quite an incredible one. As Sipho Seepe noted in Business Day on Wednesday "There was a time when Mbeki spoke and the ANC followed. In its power-drunk stupor, the ANC gave him the powers to fashion government at national, provincial and local levels."

Even after his disastrous challenge to the Western orthodoxy of HIV/AIDS in 2000 and 2001 the basic loyalty of the ANC to its leader still seemed fundamentally intact. Internal party critics such as Jeremy Cronin and Blade Nzimande were fortunate to survive a determined effort to block their re-election to the ANC NEC at the 2002 national conference. At the same time creatures of Mbeki's patronage such as Manto Tshablala-Msimang and Smuts Ngonyama both did well in the voting for that body.

Following the ANC's election victory in 2004, Mbeki was pictured on the cover of one magazine "bestriding South Africa like a colossus." Not only had he secured a 70% majority for the ANC, but the economy was prospering and he was in unchallenged command of both party and state. It should have been a relatively simple matter for him to have secured, first, his re-election as ANC president; and then, a constitutional amendment to give himself a third term in office.

As Seepe points out, the collapse of Mbeki's authority can be traced back to sacking of Jacob Zuma as Deputy President and the subsequent rebellion against him at the ANC's National General Council in 2005. The Sunday Times (July 3 2005) reported on that event under the headline: "ANC turns on Mbeki: Party hails Zuma and rejects President's reforms and policy proposals."

The Mbeki-ites had gone after Zuma, from 2000 onwards, using "salami tactics" - "demanding a little more each day, like cutting up a salami, thin slice after thin slice." The last slice, which was supposed to have finished Zuma off, was the successful conviction of his financial advisor, Schabir Shaik, on corruption charges.

These tactics misfired for a number of reasons. Mbeki's deep involvement in South Africa's massive arms deal in 1998 - and his determined efforts to scupper the 2001 investigation into it - meant that his action against Zuma lacked moral weight (whatever the actual merits of the case.)

The perception of many in the ANC that Zuma was being politically (and unfairly) targeted came down to a question of simple arithmetic. In his judgment Hillary Squires noted that from 1994 onwards Shaik had paid over a total sum of R1,34m to Jacob Zuma "and the State claims that this was done corruptly, the object being to influence Zuma to use his name and political influence for the benefit of Shaik's business enterprises or as an ongoing reward for having done so from time to time." By contrast BAE was meant to kick back some R3bn in "secret commissions" on its R27bn share of the arms-deal (of which just under R1bn has been paid over so far).

Mbeki also left his decisive move too late. By 2005 the ANC was already beginning to look beyond him. Mbeki's control over patronage - his ability to ‘reward his friends and punish his enemies' - began to lose its efficacy once uncertainty crept in as to whether he would still be around after 2009. Zuma meanwhile had, as the party's no. 2, built up a legitimate claim to be the next ANC president. Cosatu and other disgruntled elements in the Tripartite Alliance could back him without being tainted as disloyal to the ANC.

Lastly, as soon as the ANC realised there was an alternative Mbeki's contemptuous rule became intolerable. As Alexis De Tocqueville observed, "The inevitable evil that one bears patiently seems unbearable as soon as one conceives the idea of removing it."