The DA's national elections manager Jonathan Moakes says though the party may have had "racial nationalists" vote against it, there has been a "significant shift" of black voters to the official opposition.
In a letter to party structures, Moakes says he wishes that he could have written the letter "with enormous growth under our belt", but that the party's position is "solid and stable".
News24 projects the DA to receive 20.8% of the vote, down from 22.2% in 2014. It is the first time since 1994 that the DA would have failed to grow its voter base in a national election.
In contrast the Freedom Front Plus has shown a remarkable increase in support, more than doubling its share of the vote and will secure support of at least 2.5%, according to News24's projection model.
In the letter, Moakes says the DA stood alone in building a united South Africa "where moderate, liberal voters" have a future where they can collectively oppose radical politics.
"But most importantly in this election, the trends are showing us that a significant shift toward the DA has taken place among new voters who align with our values. These are mostly young, black, coloured and Indian South Africans," Moakes writes.
Statistics by News24 elections analyst Dawie Scholtz, based on the latest representative numbers, however, show that the DA seemingly has not made any significant inroads among black voters.
According to his analysis, the DA had the support of 4.9% of black voters' support in 2014 and 5% this year.
Seemingly referring to the party's electoral losses - with much of those apparently going to the FF Plus - Moakes writes the party might, in future, no longer appeal to "racial nationalists".
"Some may have seen this election as an opportunity to vote against the DA for reasons which must be interrogated, but ostensibly may include an absent DA presence in their area or non-responsiveness to delivery issues raised by residents to the party."
FF Plus national executive member Phillip van Staden says the party's experience was that many of the more than 200 000 new votes his party received were former DA voters who felt alienated and neglected by the DA.
"And it wasn't just conservative or 'right-wing' voters that came to us. We had historically loyal DA voters, some who came with the PFP and DP and never voted Nationalist but have now voted for us."
Mmusi Maimane, DA leader, on Thursday said he was "content and comfortable" about the party's performance.