The opposition is set to lose control of Cape Town which is the only major city in South Africa not run by the governing African National Congress.
Helen Zille became mayor in a tight contest earlier this year
The regional minister responsible for local government, Richard Dyantyi, has indicated he will replace mayor Helen Zille with a committee system.
The opposition Democratic Alliance has protested saying ending their control of Cape Town threatens democracy.
"The ANC is seeking to force its way back into power," Ms Zille said.
"It is refusing to play the role of opposition as parties that lose elections in democracies are required to do," she told reporters.
In tight elections in March this year, the DA secured the support of the smallest parties on the council to gather 106 votes in favour of Ms Zille, against 103 for the ANC's candidate.
Ms Zille described the plan the "biggest test for democracy" since the country's first democratic elections in 1994 and has threatened to take the matter to South Africa's highest court.
The ANC said in a statement in support of the plan that there was "a need for an inclusive system that will be representative of all the people of the city".