The by-election was to replace the vacant seat after the incumbent MP, David Ong, suddenly resigned due to his extramarital affair.
On 12 March 2016, David Ong suddenly resigned from politics as an incumbent Member of Parliament from the People's Action Party (PAP) citing "personal reasons", and having admitted on committing a "personal indiscretion", which was accepted by the party's secretary-general and Prime Minister of Singapore Lee Hsien Loong.
[4] The explanation offered by the Singapore media revealed Ong was having an extra-marital affair with a 41-year-old PAP member and grassroots volunteer Wendy Lim.
[8] The role handling Bukit Batok SMC is tentatively taken of by incumbent Member of Parliament of Jurong Group Representation Constituency and Senior Minister of State Desmond Lee pending the result of a by-election electing a new MP.
[16] Three other men had applied for political donation certificates but were not nominated as candidates:[17] Five opposition parties, including the PPP, had earlier ruled out contesting in the by-election.
By 21 April, Chee had put together a team of four to advise the SDP (in the first 100 days) on how to take over and run the town council should they win.
[24] On 24 April, Pillai revealed a plan by the PAP Jurong-Clementi Town Council to upgrade infrastructure around Blocks 140 to 149 of the SMC, which would cost $1.9 million.
[27] After Pillai said the $1.9 million funds would be disbursed regardless of the party of the by-election winner, Chee said that he would continue with Ong's masterplan, but also propose new additions including zebra crossings and covered walkways.
For the third domain, a 'health cooperative' would be implemented to help "sandwiched families" by increasing medical literacy and subsidizing consumables for the elderly.
Additionally, Pillai also proposed an "emergency button scheme" for "elderly living alone" to alert "neighbours or community volunteers" of a need for help.
[33] On 27 April, Chee pledged that if elected, he would be a "full-time MP"; making the comparison: "... every morning when Mr Murali wakes up, his first destination will be his office.
He also replied that PAP MPs have been able to juggle being an MP with an additional "day job"; while residents could not be served by just one person and a "team approach" is needed.
[42] Finally, Pillai said that if he were elected as a Member of Parliament, he would raise the issues of tightening the criteria for receiving employment passes and fighting for higher Eldershield insurance payouts for the disabled.
[43] On 4 May, Chee said that his party's "comparative advantage" would be evident in Parliament, where he could make a "qualitative difference", challenging ministers to "justify their positions" on issues.
Amongst the national issues Chee would champion discussing include the Central Provident Fund, financial assistance for the elderly, fixing and extending the progressional wage system, and retrenchment insurance.
The results was announced by returning officer Ng Wai Choong at 11.27 pm (SGT) that PAP candidate Pillai was named the candidate-elect with 61.21% of the votes, beating SDP Chee's 38.79%.