Speculation on the ground of a September general election has been further stoked by the disclosure last Monday that the Electoral Boundaries Review Committee had been formed two months ago.
There is no requirement for a formal announcement to be made when the committee is formed.
But Prime Minister Lee Hsien Loong made the revelation in Parliament when replying to questions from two MPs.
MPs and activists from the ruling People's Action Party (PAP) say they have not had any early notice, but have been gearing up all the same for the possibility of polls in September - which, in the calculations of many, is the earliest window.
Chua Chu Kang GRC MP Zaqy Mohamad says September is one of the "natural windows" during which to hold an election as there is a week-long school break during that month.
"Elections are usually reliant on schools to be polling stations and teachers to man them," he says.
Mr Zaqy adds that there are other such natural windows - in November and March next year, for instance. But he feels it is best to have the polls sooner rather than later to avoid voter fatigue arising from continual speculation.
"Having it early will be good, largely because the public has been anticipating the election for some time already," he said.
The September school holidays are from Sept 5 to Sept 13.
And although Sept 12 is the last day of the month-long Hungry Ghost Festival - a period that some conservative Chinese view as inauspicious - Tanjong Pagar GRC MP Chia Shi-Lu does not think it will be "an impediment to the election".
"For better or worse, the observance of the tradition is becoming less pronounced across the board," he says.
Dr Chia, an orthopaedic surgeon at Singapore General Hospital, adds: "People go to hospitals now even during the festival - a practice some might have avoided before. Our operating rooms on the first day of Hungry Ghost month are full, and not just with other races."
Opposition parties say they, too, are working on the assumption of a September election. But they rule out that Polling Day will be any time between Sept 18 and Sept 20 because that is the weekend of the Singapore Formula 1 Grand Prix.
National Solidarity Party president Sebastian Teo says his party has prepared logistics needed for the hustings, such as the stage backdrop for election rallies, and sourced quotations on the price of campaign posters.
"People on the ground have been mentioning Sept 12 as a possible date during my walkabouts," he says.
Political watchers also cite the carry-over, feel-good factor from the SG50 celebrations on Aug 9, and possible major announcements at PM Lee's National Day Rally on Aug 23.
Despite his early preparations, Mr Teo reckons an election is more likely towards the end of the year.
He notes that before elections were called in 2006 and 2011, the Electoral Boundaries Review Committee worked for four months before submitting its report. The elections were then called within two months. Using this time frame, the earliest possibility would then be after mid-November, when the O-level exams have ended.
But the second half of November is a busy diplomatic period, with three regional and global summits taking place from Nov 15 to Nov 22 and which involve PM Lee and other ministers: The G-20 meeting is in Turkey and Singapore has been invited to attend; the annual Asia-Pacific Economic Cooperation summit is in the Philippines; and the ASEAN summit in Malaysia.
Singapore Democratic Alliance chief Desmond Lim is also not banking on a September election.
"Certainly there is urgency to hold the election this year to ride on the SG50 celebrations. But the ground may not be that sweet for the PAP," he says.
Mr Lim points to the massive July 7 breakdown of MRT services on two of the network's main lines, and last week's annual report by the Auditor-General, which flagged lapses in financial governance in some public bodies, as events that may affect public opinion of the PAP.
For political observer and opposition veteran Wong Wee Nam, the SG50 festivities in August are a factor that works against a September election. "It's strange to have a happy celebration of the golden jubilee, and then suddenly switch to fierce partisan arguments (at the hustings).
"It's not unifying for Singaporeans," he says. "Some will also think the PAP is being opportunistic by holding an election so quickly after National Day."
Singapore Management University law don Eugene Tan says a September election "will open the PAP to accusations of not being fair and could backfire" as there will be little time for the opposition parties to respond to electoral boundary changes. He also cites what PM Lee said in Parliament last Monday: "To the maximum extent possible, we will make sure that there is enough time elapsed so that everybody can read the report, understand it and know where they stand before elections are called."
Associate Professor Tan says: "Given PM's assurance, a year-end election in late November or December, or in the first week of January, is very possible."
This article was first published on July 19, 2015.
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