South Africa's radical opposition party, the Economic Freedom Fighters (EFF), appears to be on a downward spiral after another high-profile member defected to ex-President Jacob Zuma's party.

Dali Mpofu, an advocate and former EFF chairperson, told local media that after much "soul-searching" he had decided to join uMhkonto weSizwe (MK), or Spear of the Nation.

"I believe it [MK] is the vehicle which will achieve the much needed black and progressive unity," he said.

Led by the firebrand Julius Malema, the EFF had strong support among South Africa's burgeoning young population frustrated with the slow pace of political and economic reforms since the end of the racist system of apartheid in 1994.

But the EFF suffered a major setback in the May general election when, instead of achieving its goal of rising from the country's third biggest party to second, it dropped to fourth.

It lost support to MK, in the first election the party contested after its formation last year.

Zuma spearheaded the party's campaign, making a dramatic comeback after he was imprisoned in 2021 for contempt of court over his refusal to co-operate with a judge-led inquiry into corruption during his presidency.

The two parties share similar economic policies - including the expropriation of white-owned land and the state ownership of mines and banks.

South African political analyst Sandile Swana told the BBC that Mpofu's move was driven by "political ambition".

"As it stands today, MK is substantially bigger than the EFF. If someone wants power, they have a quicker route with MK," he said.

Mpofu's defection follows that of Malema's deputy, Floyd Shivambu, and two lawmakers, Mzwanele Manyi and Busisiwe Mkhwebane.

Mr Swana said the EFF could benefit from this "pruning process".

"The unnecessary branches are being cut off," he said.

Responding to Mpodu's defection on an EFF podcast, Malema said it did not come as a shock.

"We respect his decision," he added.

But Shivambu, once the EFF leader's right-hand man, rubbed salt into Malema's wound, sharing a message on Instagram to welcome Mpofu into MK.

"Welcome Dali Mpofu to the movement which has superior ideological, political and organisational capacity, composure," he wrote in a post.

Mpofu used to be part of the EFF's top leadership, holding the post of chairperson from 2014 to 2019. He later focused on his legal career, representing the party, and more recently Zuma, in court battles with the government.

Both the EFF and MK are offshoots of the African National Congress (ANC), which has been in power since the end of apartheid in 1994.

Mpofu had been an ANC member for 33 years, before he joined the EFF.

Announcing his defection on the public broadcaster, SABC, Mpofu said he had not informed Malema beforehand, but there was no "bad blood" between them.

He also claimed that he and Zuma had first discussed the idea of forming a new party two years ago.

He helped choose MK's name, and was involved in discussions around its structure while still in the EFF, Mpofu alleged - although he denied that that he was operating as a "double agent".

Mr Swana said that Zuma and Mpofu were "intertwined".

Mpofu saw a "better prospect with Zuma rather than running around with a spring chicken like Malema", he added.

Zuma, 82, served as South Africa's president for nine years, until he was forced to resign by the ANC in 2018, partly because of the corruption scandals.

Malema, 43, is a former ANC youth leader. In 2012, he was expelled by the party - then led by Zuma - after being accused of being divisive.

Having launched the EFF a year later, he has been at the helm of the party ever since.

He is expected to be re-elected unopposed at a party conference next month, despite rumblings about his leadership.

"There is a rejection of the dictatorial style of Julius Malema in terms of leadership succession," South African political analyst Ongama Mtimka told the BBC.

He added that EFF members believed that Malema and his close circle had already hand-picked leaders for senior positions.

"If leaders get wind that their fellow leaders want to run for the top position - it's seen as a betrayal," he said.

On X, Malema alluded to more defections, cryptically posting that "they sing beautifully and are always willing to pose for pictures and sign roll calls, but remember, their souls are long gone".

Urging party members to rally around him, he added: "To prevent any potential hurt, it’s crucial to heed the guidance of the leadership.

"We remain standing and are not going anywhere under a criminal syndicate."