The amendment would allow a new government to be formed under a September power-sharing deal with MDC leader Morgan Tsvangirai as prime minister. The agreement is widely seen as the best hope of saving Zimbabwe from economic collapse.
"We have reached an understanding, an agreement on the draft constitutional bill, pending consultations and endorsement by our different leadership organs," MDC spokesman Nelson Chamisa told Reuters.
"The draft constitutional amendment bill is just one of a number of issues that have been on the table. These issues, including the sharing of some cabinet posts, the appointment of provincial governors and other senior government positions, have not been resolved," Chamisa said.
"On our part, the MDC leadership will meet next week to discuss this, and give a direction as to how we are going to proceed."