The African National Congress (ANC) looked set on Thursday to lose the parliamentary majority it has held for 30 years, as partial election results suggested it would need a partner to stay in power - a first in South Africa's post-apartheid history.

If the final results confirm the loss of its majority, the ANC will be forced to make a deal with one or more other parties to govern - a situation that could lead to political volatility in the coming weeks or months.

"There will be checks and balances on the ANC power, but the ultimate risk is that the infighting could make governance ineffective," said Simon Harvey, head of foreign exchange analysis at Monex Europe.

With results in from 20.4%% of polling stations, the ANC's share of the vote in Wednesday's election stood at 43.4%, with the pro-business Democratic Alliance (DA) on 24.8%, data from the electoral commission showed on Thursday.

The Marxist Economic Freedom Fighters (EFF) party was on 8.8%, while uMkhonto we Sizwe (MK), a new party led by former president Jacob Zuma, was snapping at its heels on 8.1%, with support concentrated in Zuma's home province of KwaZulu-Natal.

Pollsters and two of the country's three main broadcasters were predicting that the final results would confirm that the ANC - which won 57.5% of the vote in the previous election in 2019 - has lost its majority. 

While early results skew towards rural areas where the ANC is relatively strong, results from urban centres where it is weaker build up later.

"I don't think it's likely for the ANC to reach a majority," said pollster Reza Omar of Citizen Surveys.

The ANC has won national elections held every five years since the landmark 1994 election, which marked the end of white minority rule and the ascent of Nelson Mandela as president.

But since those heady days the ANC's support has declined because of disillusionment over issues such as high unemployment and crime, frequent power blackouts and corruption.

Under South Africa's constitution, the newly elected National Assembly will choose the next president. With the ANC still on course to be the largest party, that is likely to be its leader Cyril Ramaphosa, the incumbent.

However, a poor showing could make him vulnerable to a leadership challenge from within party ranks, whether in the immediate future or at some point during his term.

Which of the opposition parties the ANC may seek out as a potential coalition partner was the subject of intense speculation at the results centre in Midrand, north of Johannesburg.

"That is the million-dollar question hanging around the floor at this moment," said Susan Booysen, research director at the Mapungubwe Institute for Strategic Reflection, a think-tank.

She said there was no obvious path for the ANC, which liked neither the EFF nor MK despite some policy similarities. Both are led by former ANC figures who have fallen out with the ruling party's leadership.

The ANC may reach out to the DA, but that could prove a bumpy ride as the parties are far apart on policy and fiercely antagonistic.

RISK OF GRIDLOCK

The ruling party issued a statement that gave little away.

"The ANC looks forward to a clear mandate from voters to continue the work of transforming South Africa," it said.

Zuma's MK, in contrast, adopted a triumphant tone, slamming what it called "Ramaphosa's dismal regime" and setting out its own policy stall, which echoed some of the goals the ANC pursued during Zuma's term as president.

"The MK party remains committed to honouring your trust and working tirelessly to ensure that the vision of free education, expropriation of land, job creation, poverty eradication, youth entrepreneurship and the ushering in of a new Constitution ... becomes a reality for all South Africans," it said.

Zuma was forced to quit as president in 2018 after a string of scandals and has since fallen out with the ANC leadership, leading him to throw his weight behind MK. The party, named after the ANC's armed wing from the apartheid era, appeared to be costing both the ANC and the EFF votes.

With South Africa entering uncharted political territory, Harvey said the speed at which a coalition could be formed would be an indication of what was to come.

"If it is protracted, you may start to worry about a political gridlock going forward," he said.

The uncertainty weighed on South African markets. 

The rand slipped more than 1% against the US dollar while the wider equity index dropped more than 2%. The country's international bonds also fell.

By law, the electoral commission has seven days to declare full results, but in practice it is usually faster than that. In the last election, in 2019, voting took place on a Wednesday like this year and final results came on the Saturday.

The new parliament must convene within 14 days of final results being declared and its first act must be to elect the nation's president.