The first black leader of South Africa's largest opposition party, the Democratic Alliance (DA), has resigned.
Mmusi Maimane said that despite his best efforts, the traditionally white party was not the "best vehicle" to create a united South Africa.
Mr Maimane will remain a DA member of parliament.
On Monday, another black politician, Herman Mashaba, resigned from the DA and as mayor of Johannesburg over the party's handling of race relations.
Mr Mashaba had said his decision was sparked by the political comeback to the DA of Helen Zille, a white politician who provoked widespread anger in 2017 when she praised aspects of colonialism.
"The election of Zille as chair of federal council is victory for people who are opposed to my belief systems," he said.
DA federal chairman Athol Trollip, a white politcian who is a Maimane loyalist, also resigned from his post on Wednesday.
Mmusi Maimane's resignation as leader of the Democratic Alliance is a dramatic and quite possibly devastating moment for South Africa's official opposition.
He said he was stepping down as leader because he had lost faith in the party he'd led for the past four years.
He didn't quite spell it out, but strongly implied that a white minority in the party was blocking his attempts to reach out to more black voters and address their concerns about racial injustice.
The DA lost support in the last elections and is being torn apart by complex internal feuds.
Many South Africans believe their young democracy badly needs a strong opposition to challenge, or even unseat, the dominant but jaded African National Congress (ANC).
In 25 years, only the DA has ever come close. But the departure of its first black leader is a setback, to put it mildly.