One of President Jacob Zuma's wives has waded into the debate around his future as head of State by taking to social media platform Instagram, warning that " things are about to get ugly".

Springing to the defence of her beleaguered husband, who is under immense pressure to step down or face the prospect of a motion of no confidence vote or possible impeachment, Thobeka Madiba-Zuma wrote in Zulu. Her comment was roughly translated: "Don't fight with someone who is not fighting you".

"Umsholozi did not join the ANC in 1991, jumped ship nor hip hopped between the struggle and wealth accumulation," she wrote in the post about her husband who joined the ruling African National Congress (ANC) at a young age, went into exile, and rose through ANC structures and served a ten-year term on Robben Island.

The post is a thinly veiled dig at party president Cyril Ramaphosa.

"He left his home at a tender age to fight apartheid. He was prepared to pay the ultimate price. He will finish what he started because he does not take orders beyond the Atlantic Ocean," Madiba-Zuma continued.

The post had quickly gathered hundreds of comments and almost 2 000 likes.

There have been rising calls for Zuma to step down and to not deliver the state-of-the-nation address (Sona), both from within his own party and the opposition, who have in recent years disrupted the speech in protest at Zuma's presence amid myriad scandals of corruption and State capture.

In a momentous week in national politics, Parliament's presiding officers on Tuesday took the unprecedented step of postponing Sona which had been scheduled for Thursday evening, while the ANC unexpectedly cancelled a crucial national executive meeting that was supposed to provide clarity on Zuma's future.

Zuma and Ramaphosa are presently locked in talks around Zuma's future.