South Africans queue to vote outside a polling station in Soweto on Wednesday. (Themba Hadebe/Associated Press)

South Africans headed to the polls on Wednesday in an election expected to slightly weaken the African National Congress's dominance in Parliament.

Queues of the more than 23 million eligible voters began to form outside polling stations across South Africa before dawn.

Election officials said the voting, which is scheduled to continue until 3 p.m. local time, is proceeding well. Officials are expecting about an 80 per cent voter turnout.

"We are impressed by the enthusiasm of the voters which has been demonstrated," said Salim Ahmed Salim, head of the African Union election observation mission.

The ANC looked assured to win its fourth straight election since it defeated white minority rule in 1994 under Nelson Mandela, according to analysts.

African National Congress president Jacob Zuma casts his ballot at the Ntolwane primary school in the village of Kwanxamabala in South Africa on Wednesday. (Jerome Delay/Associated Press)

The election has generated an excitement not seen since South Africa's first multiracial vote in 1994, and is expected to propel ANC leader Jacob Zuma, 67, to president when Parliament elects the person to fill the position on May 9.

"It isn't like the previous elections," said Archbishop Desmond Tutu, a Nobel peace laureate who has been critical of Zuma. "So many people are having to ask questions but that is healthy for the democracy."

The issues in the election are different for a generation that has grown-up post-apartheid, political analyst David Monyae told Reuters.

"We are entering a post-liberation era. People are talking about new issues and challenges and there's also a new generation that's not attached to the liberation struggle," Monyae said.

But analysts have suggested the ANC will still win between 60 per cent and 66 per cent of the vote. It won nearly 69.9 per cent of the vote in 2004.

Going into the election, the ANC held 297 seats in the 400-member Parliament.

During the campaign, the ANC has faced challenges from opposition parties that have been trying to capitalize on frustration over corruption, poverty and crime in the country.

'They have forgotten about us'

The governing party has been accused of moving too slowly over the last 15 years to improve the lives of South Africa's black majority.

"I don't think the country has improved one bit. We went from a British government to a white government to a black government," said Cape Town voter Thomas Lotts, 70. "We've gone from one greed to the next. Freedom comes with responsibility and they [the ANC] have lost the sense of what freedom is about."

Voters line up in Soweto. Jacob Zuma, likely to be South Africa's next president, is eager to set up a new government that he says will bring 'visible change' to improve the lives of the country's black majority. (Denis Farrell/Associated Press)

Zuma's predecessor, Thabo Mbeki, was forced to step down last year as South Africa's president after he was defeated in a bitter power struggle for the party leadership. Kgalema Motlanthe was appointed president of a caretaker government until Zuma could take over.

Mbeki supporters broke away to form their own party late last year, the Congress of the People, which was seen as a strong challenge to the ANC, but it has had little time to prepare.

"I'm looking for a government that's going to be honest and not going to discriminate or promote corruption," said Johannesburg voter Gareth Mashigo, who cast his ballot for the Congress of the People.

The party is competing with the official opposition, the Democratic Alliance, for second place.

Under its new leader, Helen Zille, a white South African, the Democratic Alliance also hopes to boost its presence in Parliament, and has campaigned under a "Stop Zuma" slogan, aiming to attract voters uneasy over the ANC's record on corruption.

"We obviously want someone we can trust, someone who has morals and won't disappoint us. I think the youth will vote for opposition parties," 19-year-old Buhle Nchukana told Reuters.

Results expected late Wednesday

The opposition has tried to paint the populist Zuma, a former anti-apartheid guerrilla who has survived sex and corruption scandals, as corrupt and anti-democratic.

Analysts have suggested the campaign by the opposition and voter frustration could see the ANC lose its powerful two-thirds majority in Parliament. Without it, the ANC will not be able to enact major budgetary and other legislation unchallenged or change the constitution.

Poll results are not expected until late Wednesday night.

The ANC sees Zuma as the first leader since Mandela who is able to connect with voters.

During the campaign, the ANC has stressed its commitment to create jobs and a stronger social safety net for the country of nearly 50 million, which is plagued by poverty, unemployment and an AIDS epidemic.

But South Africa is expected to enter its first recession in 17 years, as its mines and factories have been hard hit by the global financial crisis.

There has been worry from some sectors that Zuma, whose alliances lie with the country's Communists and trade unions, may retreat from market-oriented policies of his predecessor. But Zuma has warned that the global financial crisis may make it hard for the ANC to keep its promises of heavy public spending.

Zuma said there won't be major changes in government policies. Despite the ANC's leftist roots, the succession of governments has broadly abided by free-market principles.

Investors are keen to see long-standing Finance Minister Trevor Manuel stay on to lend some credibility and continuity to Zuma's government. But Zuma said Tuesday it was too early to name his cabinet.

Zuma said his new government would emphasize "openness, dialogue, as well as inclusiveness."

He added that a transition team was already at work on such issues as allotting cabinet duties. He promised a more responsive and efficient executive.

With files from The Associated Press