"We will endorse those we have identified as the core of the Polokwane collective – the current president [Jacob Zuma], deputy president [Kgalema Motlanthe] and the secretary general [Gwede Mantashe]," Cosatu's central executive committee (CEC) said in a statement.
"In our assessment the other comrades have not assisted us in taking forward the Polokwane resolutions – in particular the national treasurer [Mathews Phosa] and the deputy secretary general [Thandi Modise]."
The decision was taken at a special two-day CEC meeting at Cosatu's Johannesburg headquarters, which started on Monday.
Nominations for the ANC leadership were deferred to the CEC during Cosatu's national congress last month.
This was after some of its affiliates proposed that the discussion on the ANC's leadership be opened, sparking heated debate. The proposal was rejected.
Zuma would stand for a second term as ANC leader at the ANC's elective conference in Mangaung in December.
Change in leadership
Some in the ANC had called for a change in leadership and wanted Motlanthe to take the top position.
Some ANC structures had nominated Motlanthe for the top job. He had not indicated whether he would accept the nomination.
Cosatu would have 25 non-voting delegates at the national conference. However, it had influence over its members, many of whom were ANC members, and who would be at the conference as voting delegates.
The federation also supported Zuma during the ANC's last elective conference in Polokwane in 2007, when former president Thabo Mbeki was unseated. Cosatu said it did not want the ANC to be taken over by a "new class of tenderpreneurs".
A tenderpreneur is someone who uses their political power to obtain government contracts.
"In identifying this collective [leadership] we are not in any way suggesting that it is perfect with no weaknesses of its own, collectively or individually," it said.
'Taking us forward'
"We believe that this nucleus has the best possibility under the circumstances to take us forward in the manner as categorically stated by our congress."
Cosatu said the CEC would meet again to discuss who should be on the ANC's national executive committee (NEC).
"[The CEC will] discuss the composition of the ANC NEC as a whole, including identifying comrades within our ranks who are active and fully paid-up members of the ANC for nomination into the NEC."
During the ANC's national policy conference it was proposed that the NEC be cut from 80 to 60 members.
Some union bosses reportedly had their eye on NEC positions.
Elsewhere, Cosatu general secretary Zwelinzima Vavi on Wednesday told a University of South Africa lecture that South Africans were "rapidly forgetting" the traditions created during the fight for democracy.
"We are rapidly forgetting the traditions of our movement, which valued service to the people above any thought of personal advancement," Vavi said in Johannesburg.
"The squalid morality of the capitalists, based on 'me first' and survival of the fittest is seeping even into our own revolutionary movement, dragging in its wake huge problems of factionalism and even assassination of opponents and whistleblowers."
He said a black elite had emerged out of apartheid to create "an oasis of opulence" for themselves.
"They have access to world class hospitals thanks to private healthcare. Their kids play on the same rugby fields as descendants of the Oppenheimers and Ackermans of this world."
This group was becoming arrogant and growing dangerously powerful.
Opposed to submission
The country's service delivery protests and labour strikes were a sign that the poor were not a domiciled or subservient class, Vavi said.
"They have chosen fighting as opposed to subservience, resistance as opposed to submission. Which side are you going to be on?" he asked.
He said South Africans achieved a "political breakthrough" in 1994, but failed to achieve a similar breakthrough in economic transformation 18 years on.
"Inequality has now risen to a level that has made us the most unequal society in the world."
Multinational mining monopolies were making billions of rands in profits thanks to employees exposed to unhealthy and dangerous conditions kilometres underground.
He said rock-drill operators at Lonmin's platinum mines performed the most dangerous job in the world.
"They face death every time they go down the shaft. Yet, before the latest increase which some of them have now won, their monthly earnings were just R5600."
By comparison Lonmin's financial officer earned R10-million a year, he said.
On August 16, 34 striking Lonmin workers were shot dead in a confrontation with police, during a strike for a monthly wage of R12 500.
"Millions of others" such as domestic, farm, and hospitality industry workers and security guards earned less than miners.
He said most people had begun to see South Africa as the world's strike capital.
"The increasing worry is that most of these protest actions are turning violent."
Vavi said nearly 50% of Cosatu members believed violence should be part of the bargaining process.
"So now the mentality is that if you want a speedier response, there must be something burning. This is not a trade union problem. This is the challenge that South Africa as a whole must deal with." – Sapa