It was widely believed of South Africa's outgoing president, Thabo Mbeki, that the only time he wasn't plotting was when he was asleep. More than his bizarre views on AIDS or even his failure to do much for South Africa's poor, it was that reputation as an inveterate plotter that finally brought him down.

Mbeki's humiliation has been very great. First the governing African National Congress (ANC) refused to re-elect him as its leader last year, which dashed his hopes of winning a third term in next year's election. But he would still have remained president until early 2009––until last weekend, when the ANC leadership, convinced that Mbeki was using the courts to pursue a private vendetta against his rival Jacob Zuma, ordered him to resign early.

Mbeki's immediate replacement as president is Kgalema Motlanthe, deputy leader of the ANC, but Zuma is universally expected to be elected president of South Africa in the election due early next year.

Mbeki's fall from grace has been spectacular but hardly surprising. He was Nelson Mandela's chosen successor, but his style was very different: aloof, intellectual, and endlessly scheming against real and imagined rivals. The upper ranks of the ANC are full of men and women who have been sidelined or betrayed by Mbeki.

He also didn't pay much attention to the opinions of the broader public, particularly in two areas that are vital for South Africa: curbing the AIDS epidemic, and creating jobs for the black poor.

His stubborn denial that AIDS is transmitted by the HIV virus delayed the state-aided provision of retrovirals to HIV-positive patients for years, and was indirectly responsible for the deaths of tens if not hundreds of thousands of South Africans. His neoliberal economic policies gave the country a relatively high growth rate (five percent last year), but created very few new jobs. Some people respected Mbeki, but nobody loved him.

What ultimately brought Mbeki down was his feud with Jacob Zuma, which was a self-inflicted wound. Zuma is the antithesis of Mbeki––he's a left-leaning populist with little formal education and a record of financial and sexual indiscretions––so it's natural that the two men should dislike and mistrust each other. But the party had forced Mbeki to accept Zuma as his vice-president, and a wiser politician than Mbeki would have gone along with that typical ANC compromise.

Mbeki didn't, and he seized the opportunity of a corruption charge against Zuma in 2005 to dismiss the latter from the vice-presidency. It was an error that finally brought Mbeki down, for it made Zuma the rallying point for all the elements in the party that could not stand either Mbeki's policies or his personality.

Even Zuma's allies suspect that there was something to the corruption charges, for his close associate Schabir Shaik is already in the third year of a 15-year prison sentence for his actions in the same case. But the government's case against Zuma depended on documents seized in a raid on his home and office for which the search warrants may have been invalid, and several judges have dismissed the case on legal technicalities connected with that issue.

Every time, the government prosecutors reinstated the charges or appealed the judgment, and to many Zuma supporters within the ANC it began to look like Mbeki's private vendetta against their man. Two weeks ago, the Constitutional Court dismissed the case against Zuma on the same technicality, and Judge Chris Nicholson openly voiced his suspicion that it was pressure from Mbeki that was keeping it alive.

When government prosecutors appealed the case yet again, the party's patience with Mbeki snapped, and within days he was gone. So now Jacob Zuma, who is, to put it bluntly, much closer to the popular stereotype of an African politician than either Mandela or Mbeki, is coming to power in South Africa.

Helen Zille, leader of the main opposition party, the Democratic Alliance, told the BBC that Jacob Zuma is "the leader of a rabble out to grab the spoils of state for their own interests", and that is certainly the fear of many people in South Africa and elsewhere. If it is true, then the country will now go down the same path of steep political and economic decline that destroyed so many other African countries. But maybe it won't.

Zuma is flamboyant, probably corrupt, and certainly ignorant. In a recent trial in which he was accused of raping a houseguest, the daughter of a family friend, who he knew was HIV-positive, his defence was a) she was asking for it, because she was wearing a short traditional wraparound, b) it was against his Zulu culture to turn down a woman, and c) he didn't use a condom, but took a shower afterwards to protect himself against HIV infection.

Corruption is nothing new in South Africa (it was rife under the apartheid regime) and neither is populism. The country has a free press, independent courts, a modern economy, and a good deal of political sophistication. The left had to get a turn in power some time, and there is some reason to hope that Zuma's worst instincts will be curbed by his allies.