Cosatu general secretary Zwelinzima Vavi said the recent overwhelming nomination of ANC deputy president as the party's next president has baffled many.
Addressing a gathering at the International Human Rights Day commemoration at Wits University, Vavi said most people who heard the results of ANC presidential nominations two weeks ago could not understand why people voted for Zuma.
Vavi said there was a massive campaign to demonise Zuma as "Satan with a long tail".
"After seven years of demonising him, some don't understand what we see ourselves in Jacob Zuma," said Vavi.
He said Zuma reflected the basic values of the South African people.
Also speaking at the event, Zuma did what he knows best - he spoke on behalf of the poor.
He said South Africa's response to HIV-Aids and crime undermined the basic rights to life and security and should be treated as national emergencies.
Zuma also said it was wrong for the rich not to help the poor. He said it was wrong for people to live in poverty a stone's throw away from security barriers protecting the wealthy.
He also said it was wrong for those living behind the barriers to live in fear.