Singapore's governing party faces a poll test this month to fill the seat of the ex-parliamentary Speaker who quit over an affair, officials said, at a time of growing criticism of its rule.
The January 26 by-election will give a new snapshot of the public mood two years after the People's Action Party (PAP), which has ruled the city-state for more than 50 years, suffered its worst general election result.
Public discontent has been rising over issues such as immigration - with foreigners blamed for overcrowding and putting pressure on public services - rising prices and a widening income gap.
The Elections Department announced the by-election for the seat in Punggol East ward, which had been held by former Speaker Michael Palmer, 44.
He resigned from parliament and the PAP last month "to avoid further embarrassment" after confessing to the extramarital affair.
The nomination day for candidates who intend to run is next Wednesday.
The by-election may be seen as a barometer of support for Prime Minister Lee Hsien Loong, whose party retained power in the May 2011 general election with the smallest margin of victory since independence in 1965. In a by-election last year, the main opposition Workers' Party easily retained a seat in what was seen as a fresh rebuff to the PAP. In the past year, Lee has cut ministerial pay, accelerated construction of public housing and made permanent a programme to provide cash, utility rebates and medical funds for the elderly and low-income households.
Lee said he had decided to hold the by-election in Punggol East to give the residents their own Member of Parliament, before Singapore focuses back on national issues. "We have a busy national agenda this year," he said in a statement.
"The White Paper on Population will soon be debated in Parliament. Budget 2013 is around the corner. The 'Our Singapore Conversation' is translating the views of citizens into programmes to improve our lives."
Several small parties have signalled they will contest the upcoming by-election, a situation that analysts said would divide the anti-government vote.
Opposition parties have been emboldened since the 2011 general election, when the PAP's share of the popular vote fell to an all-time low of 60 per cent.
Lee announced on Tuesday that he would nominate Halimah Yacob, currently minister of state at the Ministry of Community Development, Youth and Sports, for the post when parliament sits next Monday. She will be the country's first female Speaker.
Agence France-Presse, Bloomberg