South Africa's ruling party is facing its biggest election challenge since it took power at the end of apartheid 22 years ago.

Final results of municipal elections are being announced at 6 p.m. (1600 GMT) Saturday. Races remain too close to call in the country's largest city, Johannesburg, and the capital region of Tshwane.

The African National Congress for a generation had widespread support on the strength of its successful fight against white-minority rule. But it has been challenged by corruption scandals and a stagnant economy that has frustrated the country's urban middle class.

The ANC already has lost its first major black-majority municipality, Nelson Mandela Bay. The opposition Democratic Alliance, which has roots in the anti-apartheid movement and was white-led until last year, has predicted victory in Tshwane.