Former president Thabo Mbeki has weighed in on recent developments in the DA, calling them concerning.

Mbeki said he understood Mmusi Maimane's resignation, in particular, to be linked to racism.

“In this context, I wish to emphasise that, consistent with our constitution, all our registered political formations have an absolute obligation, practically, to contribute to the national effort to make ours a non-racial country.

“It would be a matter of the greatest concern if it were, in fact, true that our country’s official opposition, the DA, is going through a leadership crisis because of a hegemonic ascendance of a racist tendency which seeks to assert policies to that end, thus to sustain colonial and apartheid social relations,” said Mbeki.

Former DA leader Maimane and former federal chairperson Athol Trollip resigned on Wednesday, after Johannesburg mayor Herman Mashaba stepped down on Monday.

The resignations come in the wake of former DA leader and Western Cape premier Helen Zille being elected federal council chair of the party on Sunday.

On Thursday, Maimane also announced that he had resigned from the DA and parliament.

Mbeki said SA would gain nothing from any negative movement, in any of the country's political parties, towards policies based on racism.

“The DA has an imperative obligation to reassure the nation, practically, unequivocally and transparently, that it is conducting and will conduct itself in terms of all its internal and public policies and programmes, in a manner which truly helps to transform SA into a non-racial country.

“This is an obligation which binds all the political parties which serve within our legislatures, without exception,” he said.

Mbeki said members of the DA must ensure that as elected representatives of the people, they faithfully discharged their solemn obligation to contribute to the building of SA prescribed in the constitution.

“Those who organise and act to frustrate the realisation of the goals detailed in our constitution must understand that they commit a criminal act against both the ordinary people in our country and the postapartheid legal order, which has sought to defend the interests of all our people, without regard to race, class, gender, sexual orientation or creed.”

TimesLIVE reported that the DA would be convened as soon as possible to elect an interim leader.

Chief whip John Steenhuisen has emerged as the front-runner for the top job. However, nominations are open until 8pm on Friday..

The interim leader and chair will be revealed on November 17.