Morgan Tsvangirai, Zimbabwe's opposition leader, accused President Robert Mugabe of "power grabbing" and has threatened to pull out of a power share unless Cabinet posts were distributed fairly.
Thabo Mbeki, the former South African president, arrives in Harare today to try to break the deadlock and salvage the fragile deal that is designed to end years of political and economic crisis in Zimbabwe.
"If this mediation fails, we will say this marriage has failed to be consummated and we cannot force things. There will be no option but to go our separate ways," Mr Tsvangirai told thousands of supporters at a rally yesterday. "I will never betray the people and give in to Mugabe.
"This deal is not about Mugabe or Tsvangirai, it's about the people of Zimbabwe." Over the weekend, the Zimbabwean President published a Government notice, allocating three key ministries to his Zanu-PF party – defence, which controls the army; home affairs, which controls the police; and finance, key to resuscitating the nation's devastated economy where even the official rate of inflation is 231 million per cent.
"An idiot wouldn't accept that," Mr Tsvangirai said. "That is not power sharing, it is power grabbing." The decision to issue such a notice ahead of Mr Mbeki's arrival spoke volumes about "Mugabe's unguarded arrogance" and his contempt for the mediation process, the opposition leader added.
Mr Tsvangirai was adamant that he wanted at least two of the three key ministries for him to be part of any power sharing deal. He argues that the less powerful portfolios allocated to him by Mr Mugabe virtually demote him to junior partner, when he won the parliamentary elections and first round of the presidential poll.
Mr Mugabe had originally pledged to the opposition the home and finance briefs, but sources close to the President said he had changed course under heavy pressure from senior military brass, who fear prosecution for their abuses in the fight to keep the President in power.
The opposition leader stressed yesterday that he did not control of the police to wage a campaign of retribution, but to ensure the restoration of law and order, a prerequisite for investment to start trickling back into Zimbabwe. Western investors have already said they will not fund a government in which Mugabe would retain significant control.
Ever since the power-sharing agreement was signed on 15 September, it has looked decidedly precarious, and it remains to be seen whether Mr Mbeki will be able to pull it back from the brink.
Sources close to the South African mediation effort rate Mr Mbeki's chances of persuading Mr Mugabe to reverse his position from very slim to non-existent. After being ousted as South African head of state, he has been severely weakened as a mediator, some believe, and now lacks the clout to rein Mr Mugabe in.