Another Cosatu affiliate leader, who spoke on condition of anonymity, said: "S'dumo said he wants to come back but I do not know on what grounds. He initially said he is not coming back but now we are being told that he wants to make a comeback among his clique."
The leader said although Losi was a credible leader, she had not developed enough to lead a federation of such magnitude.
Losi has already been nominated by the National Education, Health and Allied Workers' Union who last month said it wanted her to take over from Dlamini during a Women’s Month commemoration event in Pretoria in honour of the 100 years of ANC stalwart Albertina Sisulu’s life.
The National Union of Mineworkers (NUM), another Cosatu affiliate, said it preferred Losi to be the next Cosatu president.
"We are not aware that comrade S'dumo is willing to run for re-election. As NUM, we have already requested comrade Losi to sign the nomination for the position of the president," said NUM general secretary David Sipunzi.
"We were of the hope that comrade S'dumo is not availing himself [and] now it’s a shock to us if he intends to avail himself. However, we have heard nothing as far as that is concerned," Sipunzi said.