Just over a third (35 percent) of adult South Africans think corruption claims against Jacob Zuma, the deputy president, are an attempt by Zuma's political enemies to discredit him.

This is the finding of South Africa's most important opinion poll, the Markinor survey, released today on the eve of the fraud and corruption trial of Schabir Shaik, Zuma's financial adviser, which starts in KwaZulu-Natal tomorrow. Allegations of efforts to bribe the deputy president form part of the case against Shaik, but Zuma has not been charged.

Significantly, 47 percent of ANC supporters also think that the corruption claims against the deputy president are a ploy by his political enemies to damage him, 44 percent think he is innocent, and only one in 10 ANC supporters think Zuma is guilty.

It has been suggested publicly and privately by many political and social commentators that the doggedness of the national directorate of public prosecutions in relentlessly pursuing investigations into Shaik's and therefore Zuma's financial affairs was fuelled, at least initially, by certain politicians and business leaders. It is said that they - aware both of the ANC tradition of making the current deputy president the country's next president and of Zuma's apparent grassroots popularity - were unhappy at the prospect of Zuma taking the country's helm in 2009.

Last year, before the Hefer Commission, Mac Maharaj, a former transport minister, and Mo Shaik, a former diplomat and Schabir Shaik's brother, suggested that investigations into Maharaj's affairs were in fact aimed at destabilising Zuma and preventing him from becoming president. Maharaj had also been connected to certain of Schabir Shaik's companies.

Before the Hefer Commission was appointed, Bulelani Ngcuka, the former national director of public prosecutions, stated that there existed prima facie evidence against Zuma in connection with Shaik, but that he would not be charged. Although this let Zuma off the hook, it also deprived him of the possibility of disproving any of the allegations in an official forum.

Zuma complained of this situation to Lawrence Mushwana, the public protector, who then castigated Ngcuka for "abuse" of office.

Earlier this week, Joel Netshitenzhe, the government's chief spokesperson, said the government had noted that Zuma had consistently denied any wrongdoing and took him at his word.

"Our respect for his office," said Netshitenzhe, "and common decency dictate that we should accept his explanation."

The Markinor survey is undertaken every six months to measure socio-political indicators.

Zuma's popularity has almost doubled since his appointment as deputy president in 1999 brought him to the fore, Markinor found. And one in three South Africans is of the opinion that Zuma is innocent, but one in five believes he is linked to corruption in some way.

Markinor also found that 24 percent of ANC supporters said they did not know whether Zuma was guilty. Twenty-two percent "neither agree nor disagree" on the issue.

At present, two-thirds of adult South Africans are satisfied with the performance of Zuma as deputy president. "In fact, Zuma's popularity is firmly established, especially among ANC supporters," said Mari Harris, the Markinor director and a political analyst.

South Africans overall gave Zuma a rating of 5,62 out of 10 for his job performance. Broken down racially, blacks gave him 6,37 out of 10, whites 2,26, coloureds 4,55 and Indians 4,07. The deputy president's own party supporters give him the most credit for a job well done.

Eight out of 10 ANC supporters believe Zuma is doing a good job.

Almost two-thirds of Pan Africanist Congress (PAC) supporters share this sentiment. This support from the PAC is in stark contrast to the 31 percent support from the ANC's alliance partner, the New National Party.

Sixty-three percent of Inkatha Freedom Party supporters and 23 percent of Democratic Alliance supporters thought Zuma was doing a good job.

This latest poll, conducted in April/May this year shortly after the election, shows that in six months since November 2003 Zuma's popularity had increased by 17 percent.

"Some of this movement is due to the optimism gripping the electorate at election time," said Harris.

Personal in-home interviews were conducted for the poll with 3 500 randomly selected respondents.

With acknowledgements to Caroline Hooper-Box, Jeremy Gordin and the Sunday Independent.