With a potential meeting between Barack Obama and his ailing hero Nelson Mandela the focus of the US president's trip to South Africa, President Jacob Zuma risks looking like a third wheel.

But for a man who has often found his leadership style called into question, Zuma also has a golden opportunity to bask in their reflective glory and prove himself a statesman.

As Obama's host and the main conduit for news about Mandela's health, he is at the apex of world affairs, at least for three days.

With the world looking on, he leads the nation through a key chapter in its history, perhaps the final journey for one of modern history's most towering figures.

His role can be compared to that of US president Lyndon B Johnson who took charge following the assassination of president John Kennedy.

"It can be potentially traumatic" for the nation, said analyst Muhamed-Nur Nordien.

Independent political analyst Daniel Silke said Zuma's government is trying "desperately" to be in control of the situation.

Having been sharply criticised for not reacting quickly enough following last year's shooting of 34 miners by police in Marikana, while he was in Mozambique, Zuma has been more proactive this time around.

He cancelled his working trip to the same country in the wake of Mandela's illness.

"Being seen as competent in handling this issue is uppermost in the minds of President Zuma and the ANC leadership," Silke said.

Updates from the presidency on Mandela's health are often followed by ANC statements, heaping praise on Zuma for informing South Africans and the world on the state of Madiba's health.

More than most countries, in South Africa, the government and the ruling party are one and the same, but both hope the statements will be mutually reinforcing.

Most observers acknowledge Zuma's government has stepped up its communication skills compared to Mandela's chaotic hospitalisation in January 2011, when the vice president was forced to step in.

But it is a fine line for Zuma: while he needs to be seen to lead, he cannot be seen to make hay from Mandela's illness.

The sight of ANC supporters outside Mandela's hospital on Thursday, some in campaign tee-shirts for the 2014 presidential election, raised hackles.

In April Zuma and the ANC came under fire after visiting Mandela, who was recuperating at home following a 10-day hospital stay.

Zuma said he was "up and about", a description that was clearly at odds with televised footage that showed a frail and dazed Mandela sitting frozen in an armchair.

South Africans accused the politicians of parading their 94-year-old hero in front of cameras for their own gain.

And when it emerged recently that the ambulance that rushed Mandela to hospital on June 8 broke down, new seeds of distrust were sown.

"After that ambulance incident, I think people were beginning to say 'are we getting the real story, is Mandela still alive?' So there is uncertainty, and the ambulance story complicated issues," said Zamikhaya Maseti of Ngcubengcuka, a policy research think tank.

Zuma can use the "global focus which is on South Africa currently to perhaps improve his public image," said Silke, but he will be "very cautious and guarded" in the way he handles the Mandela issue.

Zuma and his government "clearly desire South Africa to look competent and in control, professional when it comes to handling... the aspect of Nelson Mandela's illness," said Silke.