1. GROWING POPULATION
Six constituencies have swelled as more voters have moved in since GE2011 and so they may be redrawn.
• They are the single-seat constituencies of Bukit Panjang, Punggol East and Sengkang West; as well as Nee Soon, Pasir Ris-Punggol and Sembawang GRCs.
• A new Sengkang-Punggol GRC could be formed from parts of Sengkang West and Pasir Ris-Punggol GRC.
• So too could a new Woodlands GRC from parts of Nee Soon GRC and Sembawang GRC.
• A new constituency in the west could be drawn from parts of Holland-Bukit Timah GRC - possibly Zhenghua ward - and the Bukit Panjang single-seat constituency.
2. POTONG PASIR & JOO CHIAT
Single-seat Potong Pasir and Joo Chiat, which saw close contests in GE2011, are likely to be redrawn.
• Both constituencies are electoral anomalies: Potong Pasir has too few voters, and Joo Chiat is made up entirely of private housing.
• Potong Pasir could be absorbed by Bishan-Toa Payoh GRC, and a part of this larger GRC could be made a new single-seat constituency.
• Joo Chiat could be absorbed by Marine Parade GRC.
3. FOUR- & FIVE-MAN GRCS
Several four- and five-member GRCs could be rejigged, leading to more four-member GRCs .
• The Kreta Ayer-Kim Seng ward of Tanjong Pagar GRC may be combined with parts of Moulmein-Kallang GRC to form a new Kallang GRC.
• Marine Parade GRC and Chua Chu Kang GRC may also see boundary changes .
4. ALJUNIED GRC
• The boundaries of Aljunied GRC and Hougang will most probably be left intact.
• But single-seat Punggol East may see changes as its population has grown.
For the past two months, the group of top civil servants who form the Electoral Boundaries Review Committee has been deciding on changes to the electoral map.
This traditional exercise of adjusting constituency boundaries, based broadly on population and housing shifts, is held before every general election. Prime Minister Lee Hsien Loong, responding to questions in Parliament last Monday, said the committee started work two months ago.
Given his recommendation to the committee to lower the average size of Group Representation Constituencies (GRCs) to fewer than five MPs, GRCs are set to shrink further this time round.
With other criteria to consider - such as population changes and having at least 12 Single-Member Constituencies - analysts and political watchers are expecting there to be changes aplenty.
Since the 2011 General Election, the number of voters - citizens aged at least 21 as of Feb 1 this year - has grown to 2,460,484 as of April this year.
With 87 elected MPs in Parliament now, this works out to an average of 28,000 voters per MP.
Based on this number, previous committees have traditionally applied a deviation rule of 30 per cent - that was introduced in 1980 - to determine the lower and upper limits of voters each division should have. This means that each MP should represent about 20,000 to 36,000 voters.
But within these broad requirements, there is room to play around with various combinations of GRC sizes. Will six-man GRCs be a thing of the past? And will there be more Single-Member Constituencies?
Insight looks at how voter populations of each division have changed across Singapore, to see where the 110,000 new voters are distributed across the island.
We pinpoint where the bulk of new housing developments have sprung up since 2011, to identify which wards in particular are bulging at the seams.
Insight also spoke to Members of Parliament and grassroots leaders to find out which areas make demographic or geographic sense to carve out of, or indeed cleave to, other constituencies.