“We will fill it. There are just delays with transport and security but people are still coming in,” spokesman Keith Khoza said.
Khoza said ANC supporters were delayed because of problems with trains and were eventually brought into the stadium by bus.
Before noon the religious leaders started arriving at the stadium.
Thousands of ANC supporters flocked to the stadium on Saturday to celebrate the 103rd anniversary of the ruling party.
By 10am the stadium was already half full, with many still queuing at the turnstiles outside.
One of those who turned out to celebrate the anniversary was Busisiwe Sibali.
She said she had come all the way from Coega in the Eastern Cape, where she is a ward councillor for he ruling party.
“I came because it is a very important day for our president to deliver this speech and we are campaigning for the 2016 election.
“It is a very important election because you know the DA is in power in this province,” she said, referring to next year’s local government elections.
Earlier, the Cape Town city centre was awash with the gold, green and black of the ANC as supporters scrambled to find public transport to get to the venue.
Security was tight as hundreds of city law enforcement officers, members of the SA Police Service, private security and ANC marshals maintained law and order.
Bags were searched thoroughly at access control points, slowing down the entry of people into the stadium.
Inside the stadium, DJ Bongz and DJ Finzo had people on their feet jiving to African fusion beats.