ANC secretary general Gwede Mantashe has cautioned the SACP against making decisions that could result in both members of the tripartite alliance losing supporters.
Mantashe was delivering a lecture in honour of Chris Hani in Matlosana, in the North West, on Saturday.
This month, the communist party commemorates the 24-year anniversary of Hani's death. The former general secretary of the SACP was gunned down by white nationalists outside his home in 1993.
"In the struggle for freedom you will be betrayed and that doesn't mean you must commit suicide," said Mantashe.
He said this would be the situation if the SACP decided to leave the tripartite alliance. The communist party has become one of the ANC's loudest critics, calling on the governing party to remove its president, Jacob Zuma.
Mantashe said walking away from the alliance would not be a political decision but an emotional one.
"It sounds revolutionary, it sounds left, but the next possibility is that we divide our electoral base and split it between the party and the ANC, and both of us will lose power," warned Mantashe.
He said an ANC/SACP split would have greater consequences than when splinter party Cope was formed following the recall of Thabo Mbeki as the country's president.
"If the party delivers divorce papers to the ANC... very emotional, the ANC will accept them but the effect is that we are both weak," he reiterated.
The SACP will have to grapple with a decision when it holds its national conference in June, as some - including the North West region - have previously called for the party to pursue state power on its own.
Mantashe told those at the lecture that some in the ANC felt it did not need the SACP any longer, and viewed it as a nuisance.
"I am not one of them. I know that the communist party is not a nuisance. We need it. Activists need ideological content and theory. There's no revolution you can't theorise," he said.
The ANC SG also defended himself against those claiming he attacked the SACP at his Chris Hani lecture on Friday but that he didn't want to see it sharing a platform with the "enemy".
"It's not an attack on the party. If it's a reality that it shares a platform with the enemy because it's irritated by Jacob Zuma, society will be confused," said Mantashe.
He was referring to one of the SACP's deputy general secretaries, Solly Mapaila's participation in lobby group Save South Africa's anti-Zuma march in April.
"The party has a responsibility and I can tell you Chris Hani would not run away from that responsibility," said Mantashe. -- News24