Former opposition Member of Parliament (MP), Cheo Chai Chen, died on Jun. 4 at the age of 73.

Cheo, who entered politics as a member of the Singapore Democratic Party (SDP), also served as the MP for the Nee Soon Central Single Member Constituency (SMC).

He first ran for election in 1988.

One of four opposition candidates to win in 1991 GE

In the 1991 general election, Cheo, as SDP's candidate, narrowly won the Nee Soon Central SMC seat from the People's Action Party (PAP's) Ng Teck Poo.

This made him one of four opposition candidates to secure wins that year, alongside opposition heavyweights Low Thia Kiang and Chiam See Tong, as well as SDP compatriot Ling How Doong.

However, he lost his seat to Ong Ah Heng of the People's Action Party (PAP) in 1997.

The constituency has since been merged into Nee Soon Group Representative Constituency (GRC) since 2011.

Criticised for sexist, ageist remarks in 2015 GE

Cheo later joined the National Solidarity Party (NSP) in 2006.

In the 2011 general election, Cheo was part of the NSP team that contested in the Marine Parade GRC.

The PAP team, which was led by former prime minister Goh Chok Tong, defeated the NSP team, which featured Nicole Seah, with 56.6 per cent of the votes.

In the 2015 general election, when being fielded by the NSP against PAP's Tin Pei Ling in a three-way-contest for MacPherson SMC, Cheo told reporters that Tin's status as a new mother was "her weakness" as she might not be able to devote as much attention to her constituents.

He later brushed the remark off as a joke.

Cheo also drew flak for saying that his Workers' Party (WP) opponent, Bernard Chen, the youngest WP candidate that election, was "inexperienced".

In the end, Cheo took just 0.8 per cent of the votes in the constituency, and forfeited his S$14,500 election deposit as a result.

'A gutsy firebrand & true veteran': SDP vice-chairman

Bryan Lim Boon Heng, SDP's vice-chairman, shared his condolences in a Facebook post after hearing about Cheo's passing on Jun. 4.

Lim wrote that when he ran in his maiden election in 2001, it was under Cheo, who was leading the SDP team in Hong Kah GRC at the time.

Lim shared that Cheo would affectionately call him "good brother" and treated him like one.

He was also impressed by Cheo's resilience in spite of "a tough political campaign".

"As the team leader, Mr Cheo was unfazed & undeterred by the political onslaught & handled the overwhelming pressure coolly like a true veteran. Beneath his quiet demeanor lies a gutsy firebrand who exhibits crisis leadership when the time demands for it."

Following the news of Cheo's passing, SDP also offered their condolences in a Jun. 5 statement.

"Mr Cheo was a former Member of Parliament with the SDP, during which he served both party and country with honour and courage. Our members mourn his passing, and we send our deepest condolences to his family on the bereavement," the statement read.

Top image from Mothership / Bryan Lim Boon Heng on Facebook