The political marriage between DA leader Mmusi Maimane and the EFF's Julius Malema ended when Jacob Zuma was recalled.
This was revealed by Maimane during an interview with the Sunday Times this week.
Until Zuma was removed, Maimane said, he and Malema had had a good working relationship, which had made it possible for the DA to form municipal governments in Tshwane, Johannesburg and Nelson Mandela Bay.
The EFF's attempt to pass a motion of no-confidence against Nelson Mandela Bay mayor Athol Trollip foundered this week.
Maimane said the EFF was now "cosying up to the ANC and pushing a racist agenda".
He said: "Things were fine until they removed Zuma, which begs the question: was the party formed just in opposition to Zuma? And furthermore, are they forming a new coalition with the ANC to bring chaos and a fairly racist agenda? I think that more and more the EFF are advancing a fairly racist agenda; they are cosying up to the ANC."Maimane said the DA was not about to compromise on its principles to appease the EFF.
"We do have a good personal relationship [with Malema] and we still do now. This is an issue we differ on, we differ on a policy," he said.
He said governing should be about policy and not compromising principles.
Maimane said he was firmly in charge of the DA and did not need prove himself as a black leader of a predominantly white party.
The DA is embroiled in a fierce internal debate on race and the advancement of black leaders. This was sparked by amendments, proposed by Maimane, to the party's constitution to promote diversity.
Several senior party members, among them MPs Gavin Davis and Michael Cardo, oppose the changes, arguing that these would dilute the liberal identity of the DA.
The opposition to the changes led to claims that white leaders, among them federal executive chairman James Selfe and Western Cape premier Helen Zille, called the shots in the party.
Some senior DA leaders recently expressed unhappiness at a text message during the voter-registration weekend jointly signed by Maimane and Selfe. They said this was another example of how Maimane was being undermined.
"Today they say it's Helen Zille, tomorrow it's James Selfe and so forth ... because at times there is a condemnation that a black person can lead and I want to correct that issue up front," said Maimane.
He said if he was not really in charge, he would have been facing a challenge at next weekend's elective conference...