The National Union of Mineworkers (Num) on Wednesday publicly voiced its support for Deputy President Cyril Ramaphosa to become the next president of the country.

"Comrade Cyril, we as Num and Cosatu, we are now going out to campaign for you to become president," the organisation said in a series of tweets.

"Ramaphosa will become the president of the country whether someone likes it or not."

In the tweets, Num celebrated Ramaphosa's contribution to improving the lives of workers.

"Comrade Ramaphosa brought so many changes in the country's workplaces, especially in mines. He will bring more changes when he becomes president," Num said.

Ramaphosa was Num's first general secretary when the union was launched in 1982. The union joined Cosatu, South Africa's largest labour federation in 1985.