Zimbabwe's opposition leader, Morgan Tsvangirai, hopes a power-sharing deal will work but there was a problem of trust between him and President Robert Mugabe.
Mr Mugabe and Mr Tsvangirai failed again to reach agreement on forming a cabinet after four days of talks mediated by former South African President Thabo Mbeki which ended on Saturday.
"There's nothing wrong with the deal, that's why we signed. It's only when it came to implementation that we ran into problems," he told thousands of supporters at a rally.
Officials from regional grouping SADEC will meet in Swaziland on Monday to try to help the rival parties end the deadlock.
Mr Tsvangirai said even if a breakthrough was reached, it would be difficult to ease suspicions between him and Mr Mugabe, who has been in power since 1980.
Arthur Mutambara, head of the smaller MDC faction, blamed both Mr Mugabe and Mr Tsvangirai for the failure of the negotiations.
"I have no option but to follow these two men who have failed to agree. I saw partisanship and bankrupt ambition disrupting the discourse," he said.
But the mediator, former South African president Thabo Mbeki, says discussions will continue.
Kiwi-based Zimbabweans 'not optimistic'
A Zimbabwean living in New Zealand says the breakdown in power-sharing talks was to be expected.
Benjamin Paradza was a High Court judge in Zimbabwe, and now works as a community lawyer in Wellington.
He says Zimbabweans living in this country didn't hold much hope for a unity government between the two political parties.
But Mr Paradza says the fact the talks have been referred to the Southern African Development Community has left some cautiously optimistic there will be a solution.
He says the humanitarian crisis in Zimbabwe is getting worse and the United Nations has taken too long to act.