Zimbabwe's troubled power-sharing process involving the long-ruling ZANU-PF and the majority Movement for Democratic Change focused Tuesday on the constitutional amendment required to establish the office of prime minister to lead a national unity government.

Sources in both parties indicated competing drafts of such an amendment were being drafted  by the MDC formation headed by prime minister-designate Morgan Tsvangirai and President Robert Mugabe's Zimbabwe African National Union-Patriotic Front, in power since 1980.

Political sources said the parties will send their versions of the amendment to power-sharing mediator Thabo Mbeki, the former South African president, and to the Southern African Development Community and African Union.

ZANU-PF, Tsvangirai's MDC formation and the rival MDC wing led by Arthur Mutambara have been deadlocked for weeks over the allocation of ministries in the proposed government, raising doubts about the power-sharing as enshrined in a Sept. 15 agreement.

A Southern African Development Community summit Nov. 9 proposed as a compromise that ZANU-PF and the MDC share control of the Ministry of Home Affairs, which has authority over the Zimbabwe Republic Police, but Tsvangirai's MDC has dismissed this as unworkable.

The Tsvangirai MDC has also insisted that the constitutional amendment needed to create the offices of prime minister and deputy prime minister be passed by parliament and signed into law before the unity government be formed. The SADC leaders had recommended that the government of national unity be formed without awaiting such an amendment.

ZANU-PF has warned that President Mugabe will move ahead to name a cabinet and form a government without Tsvangirai if agreement cannot be reached, while Tsvangirai for his part has warned that such a move would spell an end to the power-sharing process.

Currently pursuing a diplomatic initiative in Europe, Tsvangirai was quoted by AFP as saying the MDC would use its parliamentary majority to nullify a unilaterally named cabinet.

Spokesman Nelson Chamisa of the Tsvangirai MDC formation responded that to the contrary, the amendment must be put in place before the cabinet can be appointed.

Legal Secretary David Coltart of the MDC wing led by deputy prime minister-designate Arthur Mutambara said his formation will refrain from proposing a draft to minimize confusion.

More reports from VOA's Studio 7 for Zimbabwe...