Zimbabwe’s main opposition leader, Morgan Tsvangirai, has died aged 65. He had been suffering from colon cancer for at least two years, but his condition deteriorated rapidly in recent days despite treatment in neighbouring South Africa.

His death will be an enormous blow to the opposition in Zimbabwe, coming only months before the first elections were due to be held in the former British colony since the end of Robert Mugabe’s near four-decade rule last year.

Tsvangirai’s illness, revealed in 2016, has divided his Movement for Democratic Change (MDC) party, with three deputy leaders and other officials publicly manoeuvring to succeed the former trade union leader.

The party will have to choose a new leader and launch a campaign against a resurgent Zanu-PF, the ruling party, to contest polls that may be held as early as May.

Without its founder at the helm, the MDC is likely to face immediate instability and could even split, handing a gift to Zimbabwe’s new president, Emmerson Mnangagwa. A broader alliance of seven political parties formed last year to take on Zanu-PF could also be destabilised.

“Tsvangirai’s death will force the MDC to convene an emergency conference to sort out the differences between the three vice-leaders. His sickness meant an impasse around internal dynamics so this might force a resolution. That’s a possible silver lining to this tragic event,” said Piers Pigou, Zimbabwe analyst for the International Crisis Group.

Tsvangirai died in a clinic in Johannesburg. Elias Mudzuri, one of the MDC’s vice presidents, said on Twitter: “Dr Morgan Richard Tsvangirai has not been feeling well for some time, it is sad for me to announce that we have lost our icon and fighter for democracy. Our thoughts and prayers are with the family, the party and the nation at this hour.”