Black communities in South Africa are "very angry" with the African National Congress, Cope leader Mosiuoa Lekota said on Saturday.
Speaking at a conference in Cape Town — organised by the FW de Klerk Foundation — on "Uniting behind the Constitution", he called on opposition party voters to come out in numbers at next year's national election to vote the ruling party out of power.
The Congress of the People leader said that at the last election, the ANC had received 62 percent of the vote; opposition parties had received 38 percent.
"So we need another 12 percent to bring the ANC down to 50 percent."
He suggested the key to doing this was in the hands of the seven million registered voters who "did not go to vote", the majority of whom were black South Africans.
"They must have seen... there was something seriously wrong with the ruling party," he said.
Over the four years since the last election, "the ruling party has committed so many blunders, so many serious blunders... that the 62 percent is no longer 62 percent".
Lekota said the mood in black communities was "very angry, very upset with the ruling party".
Opposition parties, with their eyes on next year's election, were "working towards... a coalition of voters".
He also suggested opposition parties were planning a different response this year to President Jacob Zuma's state-of-the-nation address, which he is set to deliver later this month.
"When we [opposition parties] go to the state-of the-nation address, we need to do something."
"We will finalise our decision (on how to react) in a meeting on February 12... It cannot be a state-of the-nation as usual," he said.
Earlier at the conference, the Council for the Advancement of the South African Constitution (Casac) chairperson Sipho Pityana warned on inequalities that marginalised black citizens, saying these posed a threat to the country.
"Inequalities which continue to marginalise black South Africans are the most serious threat to our constitutional democracy, and undermine its credibility.
"There is an unacceptable and unsustainable gap between the vision of the Constitution and the lived reality for far too many people," he said.
Providing people with access to decent education, adequate housing and health care, and with the protection of a social security net was essential for a cohesive society and the future prosperity of the nation, Pityana said.
Other speakers at the conference included Inkatha Freedom Party leader Mangosutho Buthelezi and advocate Jeremy Gauntlett SC.
Former president FW de Klerk said South Africa remained at a political crossroads, and it was not clear which route it would take.
The country was at a "volatile" stage.
He called for a "bos beraad" to thrash out differences in emphasis and interpretation of the Constitution.