President Levy Mwanawasa – a key Mugabe critic – is recovering from a June 29 stroke.
Zimbabwe's opposition rejects calls for a unity government, however, citing perceived bias of mediator, South African President Thabo Mbeki.
Even in Africa, pressure is mounting for Thabo Mbeki to increase pressure on Zimbabwe's president.
The African Union is expected to discuss the issue in Egypt Monday, one day after Mugabe declared a 'sweeping victory' in Friday's presidential runoff, which was widely condemned as a sham.
The second round of presidential voting was marked by violence and intimidation. Voters could vote only for President Mugabe.
The opposition's pullout from Friday's vote raises pressure on Zimbabwe's leader.
Political commentators and ordinary Zimbabweans say the opposition Movement for Democratic Change's decision Sunday will save lives.
If Tsvangirai wins despite Mugabe's heavy-handed tactics, it'll be a historic victory.
In a rare interview, militia leader threatens to take over more white-owned farms and businesses.
The international community seeks to influence the Mugabe government as Army leaders orchestrate political attacks.