The party traces its roots to the main white anti-apartheid party. Its leadership and its highest fliers are largely white, even if most of its supporters are black.
“Race is the main problem for the Democratic Alliance,” says Max du Preez, a newspaper editor and political analyst.
“It doesn’t have enough black leaders in its top ranks, and race in South Africa really matters given the long and dreadful history of apartheid.”
“If record of governance was the only consideration of how you should vote, the DA should get a two thirds majority and the ANC should get nothing. But that is not how it works.
“It is about symbolism, about history, and remembering the massive inequality in society. I would love to have a DA government, but it can’t be.”
The DA denies it has a problem with race. “People are looking beyond race towards competence, [the] ability to get things done and being able to deliver – that’s the game in town and that’s going to be the game in the next election,” Mr Steenhuisen has said.
The difficulty of conducting accurate opinion polls in South Africa means election forecasts have varied throughout the campaign. But the latest figures appear to show the ANC will indeed receive less than 50 per cent of the vote.
The shape of any coalition will depend on how far below the threshold the party slips. In the mid-40s, it may be able to get over the line by joining with a few smaller parties. Below that, it will need to look for a bigger partner – and make bigger concessions.
To broaden its appeal, the DA has formed its own broad coalition of smaller parties to bring down the ANC, although it is unclear the pact will hold if the ANC starts trying to poach partners.
While Mr Steenhuisen says the ANC must go, he has not excluded a post-election deal with the party, if that’s what it takes to keep the Marxist Economic Freedom Fighters and former president Jacob Zuma’s uMkhonto weSizwe out of government.
“I’m not ruling out anything depending on what the election results are, going forward,” he said earlier this year.