Sadtu members in Limpopo released a scathing statement this week signed by its secretary, Matome Raphasha, and his deputy, Sowell Tjebane.
Cosatu general secretary Zwelinzima Vavi has expressed shock over the "unprecedented" attack on him by the union federation's most powerful affiliate – the South African Democratic Teachers' Union (Sadtu).
Vavi told the Mail & Guardian on Wednesday: "It has never happened. It is unprecedented in the 27 years of Cosatu. I was shocked, dismayed and baffled – but I'm not going to engage them publicly."
Sadtu charged that Vavi was "arrogant" and a "master of own goals". This was after he questioned the union's apparent failure to address the textbook crisis in Limpopo.
"He has grown bigger than his boots and developed a dangerous personality cult," the pair said.
On Thursday, Tjebane said the statement had been sent to Sadtu general secretary Mugwena Maluleke for approval, as was standard practice in the union.
He said the provincial branch had first approached the national secretariat, which is headed by Maluleke, to send out a press statement on Vavi's comments, but it was advised that it was a provincial matter and should be handled at that level.
Weaken and unfocus
Maluleke is close to Cosatu president Sdumo Dlamini, who supports President Jacob Zuma, and is not a political ally of Vavi. He did not answer repeated calls made to him.
The Limpopo provincial secretary of the National Union of Metalworkers of South Africa (Numsa), Jerry Morulane, said the attacks were intended to "weaken and unfocus" Cosatu as it prepared for its national congress and Sadtu must apologise to Vavi.
Cosatu will hold its national congress in September, four months before the ANC convenes its elective conference in Mangaung.
The federation is divided over whether to support President Jacob Zuma for a second term.
Vavi has confirmed that he will stand for re-election as general secretary. Given his overwhelming support among the rank and file of Cosatu, it is unlikely that his position will be contested. He enjoys majority support in Numsa and the South African Municipal Workers' Union, although the National Union of Mineworkers and the teachers' union are divided over their support for him.
Vavi said Cosatu leaders would meet with the leaders of the teachers' union on Monday to discuss the "personalised" attack.
Sadtu president Thobile Ntola said: "Our position nationally is that we respect the leadership of Cosatu and have confidence in them.
"We are behind the federation and comrade Vavi."