The UNP is of the view that parliament should adopt both the abolition of the executive presidency and a new electoral system at the same time.
However, the SLFP wants a new electoral system given priority and to consider the matter of the executive presidency later.
SLFP MPs, both in the government and the opposition, are having this view.
Its central committee has adopted a proposal that a new electoral system should be tabled in parliament speedily and adopted as the 20th amendment.
PM is firm
However, the drafting of a new constitution is presently underway, and prime minister Ranil Wickremesinghe is adamant on the need to remove powers of the executive and make the position accountable to parliament.
This is also a promise given by president Maithripala Sirisena as the common opposition candidate at the last presidential election.
If the SLFP does not give its consent before the end of this month to fulfill this promise, the PM has decided to abandon the drafting of a new constitution and announce it to the country, say UNP sources.