(Bloomberg) -- The leader of South Africa’s official opposition quit Wednesday, deepening a crisis in a party that’s been dogged by a loss in electoral support and infighting over appointments and policies.

Mmusi Maimane succeeded Helen Zille as head of the Democratic Alliance in May 2015. His departure is a blow to the party’s efforts to bolster its share of the vote among the black majority and challenge the electoral dominance of the ruling African National Congress.

“We will continue to fight. We will not step away from politics,” Maimane, who intends staying on as a lawmaker until the end of the year, told reporters in Johannesburg after a meeting of the DA’s Federal Executive Committee.

Maimane, 39, has come under pressure to resign since the DA’s share of the vote slipped to 20.8% in May elections, from 22.2% five years earlier. The party failed to clearly articulate policies that differentiated it from an ANC that’s seeking to rebuild its support after losing ground under Jacob Zuma, who was forced to quit as president early last year.

Maimane had a further setback on Oct. 20 when Zille beat his ally, Athol Trollip, to win election as head of the party’s Federal Council, one of the party’s most powerful posts. The next day, the DA’s Herman Mashaba said he will step down as Johannesburg’s mayor in November because he believes Zille’s appointment constituted a victory for a DA faction that opposed race-based redress and clashed with most South Africans’ values.

Aside from the DA, the only other significant opposition party is the populist Economic Freedom Fighters. The DA and EFF teamed up to wrest control of Johannesburg and Pretoria, the capital, from the ANC after a 2016 municipal vote.

South Africa is due to hold its next municipal election in 2021 and national elections in 2024.

To contact the reporters on this story: Nkululeko Ncana in Johannesburg at nncana@bloomberg.net;Mike Cohen in Cape Town at mcohen21@bloomberg.net

To contact the editors responsible for this story: Paul Richardson at pmrichardson@bloomberg.net, Rene Vollgraaff, Gordon Bell

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