President Thabo Mbeki is determined to protect his legacy. To achieve this, he has played a long and careful game to manage the presidential succession. He ruthlessly sidelined Cyril Ramaphosa and Tokyo Sexwale when they threatened to position themselves to succeed him. He endorsed the continuing African National Congress (ANC) chairmanship of Mosiuoa Lekota. In his apparent masterstroke, moreover, he allowed his old friend Jacob Zuma — then unthinkable as a successor — to be elevated to the deputy presidency of the ANC and of the country.

Mbeki’s actions suggested a president undecided about who should succeed him, but also a leader with too tenuous a grasp on ANC power to choose a successor by personal fiat. Yet through his actions he turned Zuma into a potential successor, and weakened still further his capacity to control the succession.

First, Mbeki’s heavy-handed management of ideological and generational conflicts within the ANC and tripartite alliance created great and exploitable discontent. Few activists in the Congress of South African Trade Unions and South African Communist Party were confident that Zuma would really advance the interests of the poor and organised workers. Political activists can do little to influence government policy — they face powerful competitors in the state bureaucracy, interest groups and expert networks. Policy shifts can be brought about only through personnel change. Leadership and candidate selection are less visible than ideological confrontation over policy, but have more far-reaching consequences. Zuma, in the meantime, assiduously courted the left and the new generation of activists.

Second, Mbeki’s actions allowed speculation to grow that he might be obliged, by circumstances largely of his own creation, to serve a third term as president. Such speculation ironically began with Mbeki’s endorsement of the rise of Zuma. So inconceivable was a Zuma presidency in 1999 that his elevation to deputy president engendered speculation that Mbeki was contemplating a third term.

The protracted dismemberment of Schabir Shaik has been accompanied by calls from Mbeki loyalists that the party presidency remain uncontested at the 2007 national conference. But with Mbeki as ANC president, the spectre of dual power — a division between state and party presidencies — would loom, and the logic of an Mbeki third term would become irresistible. For all those who fear this possibility, the necessity is now to evict Mbeki from the party presidency at any cost.

Third, Mbeki allowed an ethnic dimension to enter leadership contests. The ANC discussion document on the “national question” observes that some cadres now “engage in low-intensity tribal mobilisation, including in order to lobby support for positions in the ANC and in government”. By insisting, against Nelson Mandela’s wise counsel, that he must succeed Madiba despite his Xhosa background, Mbeki himself implanted the potential for ethnic mobilisation that some of Zuma’s supporters have been exploiting.

Finally, and most important, Mbeki expanded the office of president so as to make it an irresistible prize. In an ideal world, power would be more widely dispersed in our political system.

Under Mandela, the presidency was one part of the system of cabinet government envisaged by the constitution. President, deputy president and cabinet governed together, and many interests were reflected in policy-making.

Although it still sits astride a weak state — one unable to police its borders, stimulate employment, deliver basic public services or rein in deviant regional neighbours — the presidency’s tentacles have relentlessly spread.

In part through Mbeki’s attempts to galvanise the bureaucracy, power has gravitated from society and party to state, from local and provincial spheres to national, and from judiciary and legislature to executive. In national government, the centre of power has inexorably moved from cabinet to presidency.

Mbeki’s presidency corrals government departments into “clusters” managed by the presidency’s own “cabinet office” and policy unit. The directors-general heading national departments have become political appointees on contract to the presidency. These officials’ own Forum of South African Directors-General, chaired by the presidency’s director-general, in effect sets cabinet committee agendas. The post-1994 deputy ministers, moreover, are loyal to the president, not their cabinet seniors.

The president, of course, is also president of the ANC. Initially under the authority of the ANC’s national executive committee, but in reality at the discretion of the president, premiers are pressed on unwilling provincial comrades, failing municipalities are hauled over the coals and policy initiatives of the national government are rubber-stamped.

These institutional and political developments make the office of state president almost the only prize worth winning. Everyone wants a piece of the next president. No one dare leave such a powerful office to rivals.

The office, moreover, might become vastly more powerful. The symbolism of the presidency makes the person occupying the highest office in the land in effect above criticism. Mbeki’s spin doctors have equated personal criticism of Mbeki with racialised denigration of a black president. In the hands of a charismatic successor, the abuse of the powers of office would be far harder to contain.

Of even more concern, the presidency might become a still more assertive institution. Mbeki has been a nonfactional president, presiding over cabinets balanced in terms of ideology, region, political history and gender. He has protected the autonomy of key institutions: the treasury, in particular, continues relentlessly to curtail the spending of heavyweight ministers; and the revenue service, intelligence agencies, courts and prosecution authorities have retained a high degree of routine autonomy.

If Mbeki’s inclination has often been to disperse power between these competing sites, a successor might more ruthlessly concentrate it, remaking the cabinet in his own image, and interfering more directly in the operation of independent institutions, especially the policing and criminal justice system and the treasury.

It is to be hoped that much of the support for the now axed deputy president has been tactical. Rather than fixedly believing that this once unthinkable candidate should have succeeded, many of Zuma’s purported supporters may simply have wanted to ensure there was a real and wide contest for the highest office in the ANC.

An intolerable Mbeki candidate, they may feel, must not simply be imposed for another long decade of unbroken rule. The potential for political calculations to backfire is real and dismaying.

Butler is associate professor, department of political studies, University of Cape Town.

With acknowledgements to Anthony Butler and the Business Day.