After winning leadership of the African National Congress last year, Zuma is the clear front-runner to succeed President Thabo Mbeki when he steps down in 2009 but faces a tougher battle to keep the ANC's sweeping parliamentary majority.

Zuma, who already wields tremendous influence as the head of the ruling party, has lobbied the government to do more to fight poverty and unemployment.

While blacks are the biggest beneficiaries of anti-poverty programmes, Zuma told hundreds of poor whites he was determined to see them and others in their community get more government grants, subsidies and basic services.

Whites make up about 9 percent of South Africa's estimated 50 million people. The traditionally white-dominated Solidarity trade union says 10 percent of whites are considered poor versus 50 percent of blacks.

"As long as I live and as long as we are together, I am going to be asking them (government officials) what is happening," Zuma said during a visit to a predominantly white township on the outskirts of Pretoria.

"There is no door in government that cannot open when I knock," said Zuma.

The Zuma-led ANC is keen to court poor white voters at a time when the main opposition party, the predominantly white Democratic Alliance, is trying to increase its appeal among blacks.

The ANC traditionally wins two-thirds of the vote, a key level because it gives the party the power to usher through sweeping changes to the country's institutions.

Some polls have placed the ANC below that level since Zuma took over from the pro-business Mbeki.

Zuma, with the backing of Communists and labour, is now leaning to the left, pushing a greater state role in the economy and expansion of grants and subsidies to the poor. He said on Thursday the problems of poor whites mirrored those of blacks.

The populist agenda has chilled investors but found favour with millions of people struggling to cope with a sharp rise in food and electricity prices in Africa's richest economy.

While applauding his efforts to reach across racial lines, some whites remain sceptical of Zuma's intentions.

"Seeing is believing," said Max Mostert, 56, who listened intently as Zuma spoke in a tent packed with unemployed, elderly and handicapped whites. "We will see if he delivers. Then we might support him."

The ANC leader could be derailed by a corruption case expected to go to trial later this year. He has said he will step down as ANC leader if he is convicted of fraud, bribery and other charges connected to an arms deal.