South African opposition parties were meeting Friday and will continue crunch talks into next week to consider the ruling African National Congress’ offer to become part of a government of national unity.

ANC failed to secure a majority in last week’s highly contested election, but some opposition parties are already rejecting the party’s offer because of deep-seated divisions.

Senior officials of the main opposition Democratic Alliance, or DA, will meet on Monday to discuss the centrist party’s approach to the negotiations. The top leadership of the the leftist Economic Freedom Fighters, or EFF, party were holding talks on Friday.

Parties are under pressure to conclude negotiations and reach an agreement by June 16, because South Africa’s constitution requires them to do so within 14 days after the declaration of the election results.