"We expect the amendment should be signed within a matter of days," Maseko told reporters at a post cabinet meeting briefing.
"We will put pressure on the political principals to sign as soon as possible," he added.
The proposed amendment will create the post of prime minister for opposition leader Morgan Tsvangirai, but his Movement for Democratic Change insists that other issues still need to be resolved before it will rule with Robert Mugabe’s Zanu-PF.
Power-sharing talks were suspended in November after Tsvangirai accused former president Thabo Mbeki, the mediator in Zimbabwe’s political crisis talks, of failing to grasp the situation in the country.
But Maseko said the South African government continued to support Mbeki’s efforts.
"The government and SADC has expressed full confidence in former president Mbeki’s mediation work. The government still stands by this."
Mugabe and Tsvangirai agreed to a power-sharing deal in September after disputed elections earlier in the year.