South Africa votes on Wednesday in general elections that will see Jacob Zuma become president less than a month after the National Prosecuting Authority (NPA) decided to drop corruption charges against him.

The African National Congress (ANC), which has dominated politics since bringing Nelson Mandela as the first black president 15 years ago, is expected to sweep to a new victory with polls tipping the party at more than 60 percent of the vote.

The more than 23-million voters will cast ballots for parliament, which is due to convene on 6 May to elect the nation's next president.

As the ANC leader, Zuma is all but certain to become the fourth black president in a country still struggling to overcome the gaping social and economic inequalities left from decades of segregationist apartheid rule.

Although the party is expected to win easily, Zuma's victory has come at a price.

His intense political feud with former president Thabo Mbeki culminated in the head of state's forced resignation last year, causing a dramatic split within the party with the formation of the new Congress of the People (COPE).

"Since 1994, what we have had is a political reality of single party dominance," said political analyst Aubrey Matshiqi.

"In the past, there are those who argued that a credible alternative could only come out of a splint from the ANC. That is why there is so much interest in the COPE."

Despite the publicity surrounding its creation just a few months ago, COPE has struggled to organise quickly enough to finance an effective campaign, but is still expected to win about 10 percent of the vote.

That would make it rival the existing opposition Democratic Alliance, which scored about 12 percent in 2004, but still suffers from an image as a party for whites.

Without a formidable opposition, the ANC could become its own worst enemy, if voters turn away from the party due to its tarnished image in the wake of Zuma's legal woes.

Prosecutors announced on 6 April that they were dropping corruption charges against Zuma, despite an eight-year investigation tied to a multi-billion-dollar arms deal, due to "abuses" of the legal system by the head of the investigation.

That left hanging doubts over Zuma's innocence, even among ANC supporters. One recent poll found 51 percent of ANC supporters believe Zuma is innocent, but 15 percent expressed serious doubts.

Matshiqi said if voters left the ANC with less than 60 percent of the ballots, it would signal a major shift in South African politics.

"If they fall below 60 percent, the election will be seen as a referendum against Zuma," he said. "Below 60 percent would be a disaster for the ANC. But the chances are very few."

The controversy around Zuma has obscured the main campaign issues, on how to ensure more people reap the benefits of South Africa's political transition.

In 15 years of democracy, the economy has stabilised, helping create a new black middle class and expanding access to basic services like electricity and water.

But 43 percent of the people living in Africa's biggest economy still live in poverty, while two in five adults are without a job.

Life in formerly all-white neighbourhoods remains at the highest standards, but townships and rural areas struggle along in deplorable conditions.

South Africa has the world's largest HIV caseload, with about 5.5 million people infected with the virus that causes AIDS. After years of denying the crisis, the government now provides treatment, but only half of the people in need actually receive medication.

Then there's the staggering crime rate, with an average of 50 murders a day, leaving police overwhelmed as the backlog in unsolved cases keeps growing.

After 15 years in power, the ANC is urging voters to give the party more time to solve the nation's problems. Despite their frustrations, voters still appear loyal.