Cosatu general secretary Zwelinzima Vavi has warned the ANC and trade unions that the DA could challenge the ruling alliance's power in 2019, the Cape Times reported on Friday.
He said the fact that the Democratic Alliance had staged a protest march with some 3000 unemployed African youths "means they are gaining confidence, they are smelling something and they are saying they want to take us on at some point, perhaps in 2019".
Vavi reportedly blamed leadership failures on a lack of political consciousness among leaders who had also become distanced from the people.
"Too many of our leaders stay in Sandton, in the former whites-only suburbs and a lot of them have become visitors in the theatre of class struggle," he said in an unscheduled speech at a National Union of Metalworkers' of SA Congress in Durban on Thursday.
He said the DA was showing increased confidence.
"Already the DA has five percent of people in townships -- something unheard of in the past."
He called on leaders accused of wrongdoing within the alliance to step down rather than bring the name of the African National Congress down.
"Unless we change that, we are gone because our battles are about hands off and not about unemployment, poverty and inequality."