South Africans vote next month in a general election that could bring about the most significant political change in three decades, with the ruling African National Congress at risk of losing its parliamentary majority.

More than 27 million people are registered to cast their ballot on May 29 to elect a new parliament. The 400-seat National Assembly then chooses the president.

After spearheading the fight against white minority rule, the party of late anti-apartheid icon Nelson Mandela has comfortably won more than 50 percent of the vote in every national election since the first democratic ballot in 1994.

That might be about to change.

The ANC is struggling in the polls and is facing growing disillusionment with its rule, which critics say has failed to deliver on many of its promises.

On Saturday, President Cyril Ramaphosa, 71, defended the ANC's record, saying South Africa today was "an infinitely better place than it was 30 years ago".

He listed advances in equality and access to education, land reforms aimed at addressing racial disparities and the building of houses and hospitals.

But unemployment is at 32 percent, crime rates remain staggeringly high and decaying infrastructure -- from rail and roads to ports and power stations -- bogs down Africa's most industrialised economy.

The country's 62 million people face recurring water outages and blackouts.

The gap between the haves and have-nots is the widest in the world, according to the World Bank.

A succession of corruption scandals has further hurt the ruling party, which slid under the symbolic 50-percent threshold for the first time in the 2021 local elections.

A national repeat is likely.

An Ipsos poll released last week showed support for the ANC was just above 40 percent.

At the last general election in 2019, it won more than 57 percent.

Were it to lose its absolute majority in parliament, the party would be forced to find coalition partners to remain in power.

- Zuma wild card -

The largest opposition party, the liberal Democratic Alliance (DA), has struck an agreement with about 10 smaller parties.

But their combined forces might still not be enough to unseat the ANC.

The Ipsos survey put the DA, which has long struggled to shake off the view that it represents the white minority, at almost 22 percent.

The biggest electoral upset might come from former president Jacob Zuma, 82.

The disgruntled ANC veteran has launched a breakaway party, uMkhonto we Sizwe (MK), that threatens to seriously cut into the vote share of his former political home.

Forced out of office under a cloud of corruption, the magnetic Zuma still enjoys fervent popular support, particularly in the battleground of KwaZulu-Natal -- his home province.

Named after the ANC's armed wing during the anti-apartheid struggle, MK was practically unknown only a few months ago, but Ipsos estimated its support last week at 8.4 percent.

The ANC has unsuccessfully tried to have the new party disqualified and to stop it from using the MK name, alleging intellectual property theft.

Zuma's own ability to run has been contested due to a 2021 conviction for contempt of court.

The Constitutional Court is yet to rule on the case and the graft-accused ex-leader currently remains on the ballot.

Some MK leaders have warned riots might erupt were Zuma to be barred.

More than 350 people were killed in 2021 in protests, riots and looting sparked by the incarceration of Zuma, who had refused to testify to a panel probing financial corruption and cronyism during his 2009-2018 presidency.

Zuma was freed on medical parole just two months into his term.

"It's like we have already won," he told a jubilant crowd of supporters in his hometown of Nkandla last week.

Results should be announced within three days of the vote.