Mpumalanga premier David Mabuza has admitted they damaged the ANC by playing factional politics at the party's elective conferences that elected President Jacob Zuma party president.
In a video that has gone viral, Mabuza says their actions were wrong.
"We have caused such huge damage in fact, what we were doing was wrong," Mabuza said.
It is understood he made the comments at a provincial ANC Youth League gala dinner held in Mbombela, three weeks ago.
Mabuza, who is emerging as a kingmaker ahead of the hotly contested December conference, regrets his active participation in factional politics.
"We could have tried to unify the movement rather than entrenching factionalism," he said.
Mabuza has been endorsed by Umkhonto we Sizwe veterans association and the ANC Youth League to become the party's deputy president in December.
ANC insiders however have previously said, while he has ambitions to take over as the ANC's number two, he was reluctant to back the presidential campaigns of the two frontrunners Deputy President Cyril Ramaphosa and NEC member Nkosazana Dlamini-Zuma.
'Mistake of supporting factions'
Some have said, he was looking at backing current Treasurer-General Zweli Mkhize to emerge as the compromise president in an attempt to unite the party.
"I was active in supporting a certain faction and every time the faction that I belonged to saw the light of the day,... every time we will win."
"What we have done in Polokwane, what we have done in Mangaung cannot be repeated," said Mabuza.
In recent weeks, Mabuza has met with Gauteng, Limpopo and KwaZulu-Natal ANC leaders in a bid to unite the party amid concern that the succession battle is further fracturing the party.
He has previously been linked to the Premier league, that includes KwaZulu-Natal, Free State and North West. However reports have said the leaders who were instrumental in Zuma's ascension to the presidency are divided over who should take over the reigns. In the video, Mabuza calls for an end to factions.
"Today, factions are the norm. You are no longer free to talk to anyone. The movement has cracked, lets get out of this thing (factionalism). Let's liberate ourselves," he said.
He appealed to the League members to bring an end to factionalism and rather focus on the party's values.
ANC Youth League deputy president Desmond Moela, confirmed to News24 that Mabuza was addressing the league in the provinces. He said he was emphatic that factions don't help the party.
"He said factions don't help the organisation. They went to Polokwane and Mangaung and the organisation suffered because of the mistake of supporting factions," Moela said.
If we cant unite the organisation, the challenge will be with us in the future, he said.