In a Memorandum of Understanding (MOU) signed between joint opposition presidential candidate Maithripala Sirisena and opposition political parties, including the United National Party, it was agreed that an all-party government would be formed for a period of not less than two years, Xinhua reported.
The text of the MOU said the joint opposition will look to re-establishing democracy, good governance, social justice and the rule of law.
The tasks will be implemented within 100 days, including the abolition of the current executive presidency and the re-establishment of a parliamentary form of government.
Sirisena, a former health minister and general secretary of the ruling Sri Lanka Freedom Party led by President Mahinda Rajapaksa, left the government recently to contest the presidential poll as the consensus candidate for the combined opposition.
Former president Chandrika Kumaratunga and a few former government members have also offered support to Sirisena's campaign.
The joint opposition, in the MOU, has also noted that the current preferential voting system in Sri Lanka will be abolished and a new electoral system will be introduced.