Mugabe's ZANU-PF party goes into the new parliament stripped of a majority for the first time since independence from Britain in 1980, and needing to work with the opposition Movement for Democratic Change (MDC) to run an effective government.
MDC parliamentarians jeered and booed Mugabe when he officially opened parliament on Aug. 26 after an election in March which the opposition says he rigged to retain power.
Former South African President Thabo Mbeki is in Harare to hold talks to try to rescue the power-sharing deal he brokered, which analysts say is Zimbabwe's best hope for ending an economic crisis.
The pact, which Mugabe and Tsvangirai signed last month, is in danger of collapse because of disagreements over the cabinet. Analysts say the convening of parliament may open a public quarrel on the issue.
"It's going to be interesting to see whether the two parties are able to engage in a constructive way or whether there are some who want to slug it out," said Lovemore Madhuku, chairman of political pressure group National Constitutional Assembly.
"But I think both parties are under pressure to demonstrate some maturity, to show that they are fit for office because any kind of delinquency will be politically costly," he said.
Lawmakers are due to prioritise a constitutional amendment allowing the creation of the prime minister's post, which the power-sharing deal agreed would be filled by Tsvangirai.
Mugabe's party lost control of parliament in the March election, winning 99 seats, but the 100 seats Tsvangirai's party won do not give it an absolute majority.
That leaves the balance of power with Arthur Mutambara's breakaway MDC wing, which has 10 seats.
Mugabe was re-elected unopposed in a June vote condemned around the world after it was boycotted by Tsvangirai.
Nelson Chamisa, an MDC spokesman, said he hoped Mbeki, who arrived in Harare late on Monday, would break the cabinet impasse after Mugabe handed key ministries to his ZANU-PF party.
"We are still placing our faith in the efforts of the mediator, and that ZANU-PF has to be persuaded that it has to share and not grab power," he said.
Analysts say that although the political talks look doomed, the rivals are under intense pressure to reach a settlement.
Spokesman Mukoni Ratshitanga said Mbeki would start talks on Monday evening and meet all sides.
Analysts say parliament is expected to meet briefly and may adjourn until an agreement on cabinet posts is reached.
A new government will have to tackle the world's highest inflation rate of 231 million percent and severe food, fuel and foreign currency shortages.
Güncelleme Tarihi: 14 Ekim 2008, 11:12