The Constitution Select Committee (Copac) co-chairperson Munyaradzi Paul Mangwana said there was no way Mugabe would sign into law a document which disqualified him from contesting.
"President Mugabe has already said he is contesting the next elections. As long as I am in Copac, there is no way we are going to allow a draft which is detrimental to my party [Zanu-PF] and its leader," he said.
Copac last week published the first draft which has many sections that Zanu-PF is strongly opposed to.
According to the report, Section 6.4.2 of the draft disqualifies from standing in Presidential elections, any person who has already held the office for 10 years, meaning that President Robert Mugabe cannot contest the next polls.
The powers of the President with regards to the appointment of security chiefs are diluted and the draft also allows dual citizenship under Section 3.3, another issue strongly opposed by Zanu-PF.