Zimbabwe's main opposition party has elected Nelson Chamisa unopposed to remain as leader at its first congress since the death of its founder, Morgan Tsvangirai, the party announced Monday.The Movement for Democratic Change (MDC) has been plagued by infighting since Tsvangirai's death and battered by another election defeat.Tsvangirai appointed Chamisa and Elias Mudzuri as party co-vice presidents before dying of colon cancer in February 2018.Chamisa, 41, then took the party helm, becoming its champion in the first presidential elections since the authoritarian Robert Mugabe was ousted.He lost the 2018 ballot to incumbent Emmerson Mnangagwa of the ruling Zanu-PF, an outcome that he says was rigged."Young leaders are taking over in Africa," Chamisa told party activists in Gweru city after the party also elected new office bearers over the weekend."Change is taking place not only in Zimbabwe but across the continent."Zimbabwe's economy, which the 76-year-old Mnangagwa has vowed to revive, is once more an explosive issue, with shortages of fuel, a cash crunch and rising inflation.'We want to teach them a lesson'"We are going to modernise the party," said Chamisa who served as information and communication technology minister during a power-sharing government from 2009 to 2013."Zanu-PF has been here for a long time but we want to teach them a lesson. Our simple agenda is transformation. We want to build a nation because we only have one country."Formed in 1999, following a conference of labour, church and civic society and students groups with trade unionist Tsvangirai as founding leader, the MDC is the largest opposition party the country has known since independence in 1980. It is the only party to have posed a sizeable challenge to Zanu-PF's grip on power, often in the face of violence, but also has a history of internal feuding.In the 2008 presidential elections, Tsvangirai beat Mugabe in the first round but failed to garner enough votes to be declared winner.He withdrew from the run-off, citing attacks on his supporters by Zanu-PF militants and state agents that left around 200 people dead and thousands displaced.Earlier this month, the high court, petitioned by a party district official, declared that Chamisa's appointment as party vice-president by Tsvangirai had been illegal.The MDC said the ruling was a Zanu-PF strategy ahead of the congress and has lodged an appeal.