JOHANNESBURG, South Africa - Zimbabwe's political factions were bitterly and deeply estranged heading into a weekend summit at which regional heavyweight South Africa and other neighbors were to push them hard to share power.

Both Zimbabwean President Robert Mugabe's ZANU-PF party and opposition leader Morgan Tsvangirai's Movement for Democratic Change say they want resolution so they can turn their attention to rescuing their country from economic collapse.

But there was little prospect of a breakthrough at Sunday's summit of the Southern African Development Community, the 15-member regional bloc that has been shepherding Zimbabwe negotiations for more than a year.

South Africa, which will chair Sunday's meeting, expressed impatience with both sides nearly two months after they signed the broad outlines of a power-sharing deal under which Mugabe was to remain president and Tsvangirai become prime minister.

South African government spokesman Themba Maseko told reporters South Africa will take "quite a hard stance" on Sunday to push for resolution.

Botswana, another member of the regional bloc, has been even blunter, placing the blame for the deadlock on Mugabe and calling for new elections in Zimbabwe. That sparked charges from Mugabe's government that Botswana had trained opposition activists to destabilize Zimbabwe. Botswana denied the accusations.

Political analyst Sydney Masamvu said impatience among Zimbabwe's neighbors may be fueled by the need to focus on new crises like the conflict in eastern Congo, which also was on the agenda Sunday.

But he said leaders will find it difficult to make progress on Zimbabwe with Mugabe cronies in politics and the military resisting surrendering power -- for fear either of being dragged to court for human rights violations, or of losing access to state coffers.

In addition, Tsvangirai won't be "frog-marched into an agreement," Masamvu said. Some of Tsvangirai's traditional supporters already have accused him of giving too much by allowing Mugabe to remain president, and signing on to a deal that cannot work.

"There's no chemistry, there's no appetite for agreement," said Masamvu, southern Africa researcher for the International Crisis Group, an independent think tank.

A crackdown on dissent was intensifying in Zimbabwe, with attacks on Tsvangirai's supporters and arrests of pro-democracy protesters. Zimbabwe state media, meanwhile, accused the opposition of planning to force Mugabe from power -- unlikely given Tsvangirai's history of nonviolence and Mugabe's own bloody record after nearly three decades in power -- but a stark illustration of the distrust that separates the two.

Negotiations have stalled on appointing Cabinet ministers. Tsvangirai accuses Mugabe of trying to hold on to too many of the most powerful posts, including the police and finance ministries.

Tsvangirai's spokesman Nelson Chamisa said in a telephone interview from Zimbabwe's capital that even if they emerge from Sunday's summit with an agreement, working together in the same government is "not going to be easy."

But "people are suffering. People are dying," Chamisa said. "We need to find a way forward."

Zimbabwe Information Minister Sikhanyiso Ndlovu said in an interview that "as far as the ruling party is concerned, we should have had an agreement long ago."

But Ndlovu also repeated his government's charges that opposition leaders were being manipulated by former colonial power Britain into resisting agreement. The opposition rejects such charges as arrogant and insulting.

Opposition spokesman Chamisa said that if no progress on power-sharing was made Sunday, his faction would turn to the African Union and the United Nations to ask them to oversee new elections.

Lovemore Madhuku, head of Zimbabwe's independent National Constitutional Assembly, said ordinary Zimbabweans were ready to take matters into their own hands. His alliance of civic and labor groups plans street protests starting days after the summit to pressure Mugabe, even though protests have been violently dispersed by police in the past.

"Zimbabweans have not been listened to. The international community has not been listened to," Madhuku said. But "the most important front is the front of the people on the ground here. They must do more. That is the way forward."