The formal countdown to the next general election has begun with last Wednesday's announcement on the formation of the committee that reviews Singapore's electoral boundaries.
The Electoral Boundaries Review Committee's (EBRC) report will set out the battleground for the next general election, which has to be held by April 2021.
In the past three GEs under Prime Minister Lee Hsien Loong, the period between the announcement of the EBRC's formation and Polling Day has ranged between two and six months.
In recommending changes to existing group representation constituencies (GRCs) and single-member constituencies (SMCs), the latest incarnation of the committee will look at population changes in the various divisions.
It has been tasked to create more SMCs than the current 13, and further reduce the average size of GRCs, which were introduced in 1988 to ensure minority representation in Parliament.
Since PM Lee committed in 2009 to make Singapore's electoral system more balanced, the average size of GRCs has come down from 5.36 at that time to 4.75 in the 2015 GE.
At the same time, the number of SMCs increased from nine as of 2006, to 13 in 2015.
Insight looks at the areas that are ripe for change.
PASIR RIS-PUNGGOL/SENGKANG WEST/PUNGGOL EAST
Since the 2015 polls, the number of eligible voters has grown by 5.4 per cent to 2.59 million as of April.
Going by the numbers, divisions in the north-eastern part of the island are prime candidates to be redrawn.
The EBRC typically decides on the minimum and maximum number of voters per Member of Parliament by dividing the total number of electors by the existing number of MPs, then allowing for a generous variation of up to 30 per cent.
Based on this formula, each MP in the next election should be taking care of approximately 20,000 to 38,000 voters.
On these grounds alone, two constituencies would need to be changed because they are bursting at the seams.
With 242,225 voters as of April, Pasir Ris-Punggol GRC has swelled by almost a third since 2015, ballooning beyond the upper limit of 227,000 voters for a six-member GRC.
The growth should not come as a surprise - new Housing Board flats have proliferated in Punggol and Sengkang towns, and their status as non-mature estates makes them cheaper than homes in older towns such as Queenstown or Bishan.
Hence, these towns have been especially popular among young couples and families.
The GRC's exponential growth has prompted speculation that a single-seat may be carved out from it, or that the six-member constituency gets split into two.
Within the constituency, MP Teo Ser Luck's Sengkang Central ward, which grassroots leaders estimate to have around 85,000 residents, is said to be the largest in Singapore.
From having just one small study area for students several years ago, the third-term MP now has 13, to accommodate the rising number of teenagers there.
"These days, there are a lot more bursary award ceremonies and they go on for longer," Mr Teo said.
His colleague, Mr Zainal Sapari, who is also the GRC's town council chairman, noted that more property officers have been hired to attend to the growing number of families moving into new HDB flats and condominiums.
Said Mr Zainal of his seven years in the constituency: "We function very well as a six-man team - we haven't had issues where we thought we needed a smaller GRC.
"But if the decision is to make us smaller, then it might be a response to feedback from the electorate to give them more options," he said, adding that there has been feedback from members of the public that large GRCs make it even harder for opposition parties to field the required candidates for a team.
Observers said an obvious way to deal with the surge in population is to split Pasir Ris-Punggol into two.
Notably, the GRC has two heavyweight ministers as MPs - Senior Minister Teo Chee Hean and Minister in the Prime Minister's Office Ng Chee Meng, who is also labour chief and a key member of the fourth-generation leadership team.
Both are expected to remain in politics for some time and could conceivably head their own GRCs in the coming election.
Breaking up the six-member GRC - one of the only two such GRCs alongside Ang Mo Kio - would also be in line with the committee's directive.
In fact, it is possible for these two behemoths to both be reduced in size in one fell swoop, with the creation of a new Sengkang GRC.
Punggol East MP Charles Chong said it was possible for three new GRCs to emerge from the northeast: Punggol GRC, Sengkang GRC and Pasir Ris GRC.
"Punggol estate, once fully developed, is so big it could sustain a five-man GRC. Sengkang is close to that size, and Pasir Ris estate is smaller, maybe a three-man GRC," he said.
One development supporting this line of argument is the creation of a panel last July to oversee development for Sengkang and its 230,000 residents.
Chaired by Sengkang West MP Lam Pin Min, the panel also comprises Mr Chong, Mr Teo Ser Luck as well as Dr Intan Azura Mokhtar and Mr Gan Thiam Poh, who are both from Ang Mo Kio GRC.
It looks at areas including childcare and educational institutions, public transportation and active mobility, as well as town council and environmental issues.
Some observers see the move as a prelude to a new GRC, which will take in Sengkang West and Punggol East SMCs to deal with the new demographics.
Sengkang West is the largest SMC by voter population. It grew by almost 17 per cent in the past two years due to the influx of young families, and now has 47,891 voters. This far exceeds the upper limit of 38,000 voters set for SMCs.
Nearby Punggol East, with a similar profile, is also edging closer to the maximum voter capacity with 35,477 voters.
The ward, which the Workers' Party wrested after a 2013 by-election and ceded in 2015, is seen as a dicey ward for the ruling People's Action Party (PAP). Mr Chong had won by a thin margin of 51.77 per cent of votes in 2015.
Observers reckon it could be swallowed up by the surrounding GRCs.
But Ang Mo Kio GRC's Mr Gan downplayed the notion that the creation of the panel hinted at future boundary changes, noting the committee has always been around. Last year's announcement accommodated the increase in new flats and included the Buangkok neighbourhood.
"It's only as Sengkang has gotten bigger, that the MPs decided it was better to come together and talk to the agencies for better coordination and more efficiency," he said.
However the lines are redrawn, Mr Chong wants the EBRC to "do so sensibly, so we don't have bits and pieces of different housing estates in a GRC".
Now in his seventh term, the veteran MP notes that between 2001 and 2015, "it was a bit ridiculous to have divisions like Punggol Central and Punggol South when none of them were actually in Punggol".
After the 2015 polls, MPs renamed Punggol Central as Sengkang Central, while Punggol South became Sengkang South, a division in Ang Mo Kio GRC.
But his constituency, Punggol East, could not be renamed Sengkang East despite its location as it was designated by the EBRC.
Said Mr Chong: "It would be good if constituencies were divided along natural boundaries - like bus services and police divisions - because that's actually how infrastructure works."
"Otherwise, you might have a case when MPs have to deal with multiple authorities under different jurisdictions."
POTONG PASIR AND OTHER
SMCs Potong Pasir is the only ward among the 29 constituencies that has fallen below the minimum voter benchmark.
Its 16,739 voters is far below the lower limit of 20,000 set for SMCs.
As a constituency held by opposition veteran Chiam See Tong from 1984 to 2011, its boundaries have remained untouched for more than 30 years, even as its population continued to shrink.
This is likely because any changes to the boundaries of opposition-held areas would have gone down badly with the electorate.
Now that the constituency has been back in PAP hands for two election cycles, could it be wiped off the electoral map?
Potong Pasir MP Sitoh Yih Pin, who lost twice in the SMC in 2001 and 2006 before he finally was elected there in 2011, hopes that scenario does not happen.
The constituency is growing, he said. New developments in the Bidadari estate will add about 3,700 units.
Residents from the Alkaff Vista housing development have already collected their keys in July, and those from Alkaff Lakeview will soon follow.
While he declined to speculate if Potong Pasir might "disappear", Mr Sitoh said voter numbers in the SMC have always been below the lower limit, and yet it has remained.
It also has a long history and is one of the oldest constituencies around, having been on the electoral map since 1968.
"It would be nice to preserve it, albeit that we will be below 20,000," he said.
National University of Singapore (NUS) sociologist Tan Ern Ser reckons that the constituency will stay, as there is no compelling reason to enlarge a nearby GRC.
Another factor that works in Potong Pasir's favour is the committee's directive to have more than the current 13 SMCs.
Where will the other SMCs come from?
Political observer Derek da Cunha and NUS political scientist Bilveer Singh believe they will be carved out of PAP strongholds.
Dr da Cunha reckons six-member Ang Mo Kio and Pasir Ris-Punggol GRCs, and five-member Bishan-Toa Payoh, Nee Soon and Tanjong Pagar GRCs could all be reduced by one ward, producing five new SMCs in the process, to make 18.
"It is probable that the reduction in the size of GRCs will be done progressively and not in one fell swoop," he said.
While the increase in SMCs might be welcomed by those looking for the balance between the number of GRCs and SMCs to be shifted towards SMCs, some observers pointed out that single-seat wards are also fertile ground for potential multi-cornered fights, thus splitting the anti-PAP vote.
EAST COAST GRC
While the committee gets its terms of reference from the Prime Minister, and the main factors it is asked to consider are population changes and shifts, this has not stopped discussions over the years of political motivations behind boundary changes.
Cynics often speculate that some constituencies may be wiped out or broken up because the opposition had fared creditably in previous elections or PAP heavyweights are stepping down.
In voicing these concerns, they point to how Joo Chiat had disappeared from the electoral map and became part of Marine Parade GRC in 2015, after WP candidate Yee Jenn Jong won 48.98 per cent of votes in the 2011 GE.
Another example they cite is Moulmein-Kallang GRC, which was broken up in 2015 after then Transport Minister Lui Tuck Yew stepped down amid mounting unhappiness over rail disruptions.
The four-member GRC did not see significant demographic change, with its voters going from 87,595 in 2011 to 87,965 in 2015.
It was split up with most of its voters going to the new four-member Jalan Besar GRC. Mr Lui's Moulmein ward was mostly redistributed among three other GRCs: Bishan-Toa Payoh, Holland-Bukit Timah and Tanjong Pagar.
Speculation in the opposition circles this time around is that East Coast GRC could see changes.
It was hotly contested in the 2011 and 2015 elections, with the WP team there garnering 45.17 per cent of the votes in the 2011 contest and 39.27 per cent of votes in 2015.
This time around, the four-member constituency could see two of its MPs retire.
Former Manpower Minister Lim Swee Say, who stepped down from Cabinet last year after a reshuffle, had said on several occasions that he was ready to leave politics.
Asked during a recent walkabout in his constituency if he was planning to retire, Mr Lim would only smile.
But grassroots leaders in his Bedok ward are privately saying that they expect a new candidate to replace him.
Former Senior Minister of State Lee Yi Shyan, meanwhile, had stepped down as an office holder in 2015 after a minor stroke that year, saying he wanted to "change gear".
There is speculation that he too could leave his Kampong Chai Chee ward.
Mr Yee from the Workers' Party is among those who wonder if the GRC could be redrawn.
Said the former Non-Constituency MP: "Having gone through the sudden and unexplained absorption of Joo Chiat SMC into Marine Parade GRC previously, we have to be prepared for all contingencies.
"There will be the regular retirement of former anchor members of the GRCs in the east and with that, there may be the usual reconfiguration of boundaries."
Similarly, Associate Professor Singh reckons East Coast could see its boundaries redrawn due to the expected retirement of its veteran MPs.
But he said they are likely to be tweaks instead of a major chop and change.
There is a limit to how much the constituency can be changed, he said, given that it has already undergone big alterations in the past - going from six to five in 2006, and down to four members in 2015.
'If boundaries keep changing, they risk making the voters very angry," he added.
He believes some polling districts could be moved out of East Coast to adjoining PAP strongholds, and this may end up neutralising the threat posed by the WP.
For instance, Fengshan SMC could absorb some of the rental flats and smaller flats in Bedok, which Prof Singh said are less supportive of the PAP than the private estates.
"The Fengshan MP (Cheryl Chan) is very hardworking and very good, I've heard from my relatives, and her area already has residents of those profile," said the academic, who lives in East Coast GRC.
Observers also noted that changes to constituencies would cut both ways - incumbent MPs would also have to restart their grassroots work and outreach if their ward is changed.
ALL QUIET ON THE WESTERN FRONT
If the east looks set for some upheaval, what then of the west, traditionally seen as a PAP stronghold?
Of the 10 constituencies clearly in the west, seven surpassed the PAP's national vote share of 69.9 per cent, with Jurong GRC - helmed by then-Deputy Prime Minister Tharman Shanmugaratnam - clocking the highest percentage of votes, with 79.29 per cent.
Even the three constituencies that did not meet the PAP's vote share - Marsiling-Yew Tee GRC, Holland-Bukit Timah GRC and Bukit Panjang SMC - garnered a more-than-respectable portion in the high 60s percentage range.
Senior PAP cadres in these areas said that based on population alone, there should not be dramatic changes to the wards as the voter numbers in these mature estates have remained fairly stable.
However, the EBRC may also factor in future households moving into up-and-coming estates such as Tengah, where Build-To-Order HDB flats are expected to be ready in 2027 or earlier.
For now, any changes are more likely to be the knock-on effect of changes to other wards.
For example, in central Singapore, Bishan-Toa Payoh GRC and Tanjong Pagar GRC both boast two ministers each: Manpower Minister Josephine Teo and Defence Minister Ng Eng Hen in the first, and Trade and Industry Minister Chan Chun Sing and Minister in the Prime Minister's Office Indranee Rajah in the second.
One of them could step in to anchor nearby Jalan Besar GRC, which no longer has a minister at the helm after Dr Yaacob Ibrahim retired from Cabinet last year.
If that is the case, how these three GRCs would be regrouped would affect adjacent constituencies westwards.
Progress Singapore Party leader Tan Cheng Bock's old constituency of Ayer Rajah is currently in West Coast and some observers have said that he might return to contest the area he had won handily when he was a PAP MP.
Said Prof Singh: "We might see a chunk of Jurong GRC from Senior Minister Tharman's ward moved into West Coast GRC. And a part of West Coast GRC could also be hived off to adjoining Tanjong Pagar GRC."
These changes, if made, might end up neutralising the "Tan Cheng Bock effect" if he were to contest there, the academic added.
A senior cadre said one possibility being floated around is for Mr Chan to break away from Tanjong Pagar GRC, and form a new GRC comprising his Buona Vista ward, Radin Mas SMC and Telok Blangah ward in West Coast GRC - a spot currently held by retired minister Lim Hng Kiang.
Others suggested that labour MP Patrick Tay, who helms Boon Lay ward in West Coast GRC, is popular enough to helm a single-seat ward.
But as one cadre put it: "There are so many combinations and the plans today will change tomorrow. The point is to be prepared for all situations."
Former Nominated MP Zulkifli Baharudin said that whatever the changes, "they must be comprehensive enough and be island-wide."
"The boundary changes in themselves must be seen to be reasonable and fair," he added.