The Congress of South African Trade Unions (Cosatu) on Monday said it was not surprised that President Jacob Zuma was near the bottom of the list of South Africa's most trusted leaders.
The federation said it was inevitable that Zuma would be criticised more than other officials, because of his high profile.
Cosatu said the president often had to make tough decisions.
The index placed Zuma 23 out of 24 South African leaders who were evaluated. The only politician who scored lower than Zuma was former Congress of the People (Cope) leader Mbhazima Shilowa.
The study was conducted by the Reputation Institute in order to measure the level of trust people had in leaders.
Zuma scored just 36 percent.
Mining mogul Patrice Motsepe topped the list, with Cosatu General Secretary Zwelinzima Vavi coming in at number two.
Cosatu spokesperson Patrick Craven said they were delighted with the results.
"We are pleased that Vavi received the second highest rating in a poll about who South Africans trust most."
Deputy President Kgalema Motlanthe was third on the list. Democratic Alliance leader and Western Cape Premier Helen Zille came in at number six.