A make or break speech for Zuma?

South African President Jacob Zuma is set to deliver a crucial State of the Nation address this evening, ahead of the May election and amid a declining economy and growing disillusionment with 20 years of African National Congress (ANC) rule.

South African President Jacob Zuma
Christopher Furlong | Getty Images
South African President Jacob Zuma

Recent polls show voter dissatisfaction mounting and there have been 94 protests so far this year resulting in at least 10 deaths, according to the Institute for Security Studies (ISS). South Africans are frustrated by an unemployment rate of 25.7 percent, along with 10 million without formal housing and over 2 million without proper toilets.

All this while it emerged back in October that the state had spent more than 200 million rand ($18 million) on upgrades to Zuma's private residence including a medical clinic and helipad, which led to calls for a corruption inquiry

(Read more: South Africa's central bank hikes key rate to 5.5%)

"And so the president speaks to a country that in some areas is in no mood to listen; to citizens who are tired of waiting for 'delivery' and still others who believe corruption is on the increase and that South Africa is losing its way," wrote Judith February, a senior researcher at ISS Pretoria.

A November Ipsos poll published this week showed the decline in confidence among South Africans regarding the direction the ANC was taking their country. Whereas in 2009 56 percent saw the nation moving in the right direction, against 29 percent taking a negative view, now 48 percent see South Africa moving in the wrong direction.

The allure of the ANC

Many commentators have warned that the ANC may see its hold on the majority black electorate start to fade following the death of former President Nelson Mandela on December 5. However, Abdul Waheed Patel, managing director of Ethicore Political Consulting in Cape Town, argued that the ANC has a strong base and it was difficult to tell whether the current climate of economic disillusionment would translate into a bad result for the ANC in May.

(Read more: What Mandela meant to South Africa's economy)

"The ANC historically has this legacy of being the party that liberated South Africa from its Apartheid past, and that has always loomed large as a factor that the party can rely on when they go into an election, no matter how bad the polls are," Patel said.

Richard Drayton, Rhodes Professor of Imperial History at Kings College London, agreed. "The ANC continues to derive enormous prestige from its central role in the end of Apartheid, and remains the best organized of the political parties," Drayton said via email.

"Zuma's speech has then only minor relevance to the elections: the safe bet remains that the ANC will once again win clear victory in this year's elections. There is no nucleus of the opposition to the ANC that stands any chance of competing with it on a national scale at the moment."

(Read more: South African miners treated as 'slaves': Union head)

A changing picture?

While the ANC has a core, strong base, 20 years on from the end of Apartheid, there is clearly a subtle shift in allegiance, and a growing focus away from the past and on the present and future.

Drayton stressed the importance of the Marikana massacre in August 2012, when 44 striking miners were killed by police. In December last year, the National Union of Metalworks (NUMSA) decided not to endorse the ANC at this year's election and instead looked at setting up a rival political vehicle for social change.

Patel emphasized that "given the state of the economy, the vote will come down to bread-and-butter issues," and that inequality would be the main issue at the election.

"It is symbolic that you have a party that says its prime objective is to deliver equality for all South Africans but prime within that is to uplift the poor. Yet the poor are saying their lives have not changed much in 20 years. It is symbolically important and substantively important," Patel said.

Yet despite the economic grievances of many, there is no credible alternative to the ANC. Mamphela Ramphele, the widow of anti-Apartheid activist Steve Biko, formed her own party and joined forces with the Democratic Alliance, but last week announced she would not stand as a candidate at the election in May.

Thus, Drayton concluded: "Zuma remains in a commanding position, and his speech tonight will be made from a position of strength."

—By CNBC's Kiran Moodley. Follow him on Twitter @kirancmoodley