Former deputy prime minister and veteran politician Wong Kan Seng, 68, will not stand in the coming general election.

His decision to leave politics was announced yesterday by People's Action Party organising secretary Ng Eng Hen at a press conference, where the party introduced its candidates for the Bishan-Toa Payoh GRC.

After it was announced, Mr Wong's PAP colleagues surprised him by standing up and bowing to him as a gesture of thanks for his contributions over 30 years.

Two other MPs in the constituency will also be retiring at the next polls: Mr Zainudin Nordin, 52, and Mr Hri Kumar Nair, 49, both backbenchers known for their hard-hitting speeches in Parliament.

Mr Nair is leaving politics because his wife had been ill with lymphoma, while Mr Zainudin wants to focus on his family as well.

Dr Ng, in lauding Mr Wong, noted that he is one of the longest-serving MPs. "He has mentored a string of MPs, including myself," he said.

Mr Wong, in reply, joked that it seemed like yesterday when he was a rookie candidate introducing himself to the media in 1984.

"Over the subsequent elections, I sat at party headquarters introducing new candidates. Today, I am introducing but also (announcing) I'm no longer standing after seven terms," he said.

He introduced his replacement, who is chief executive of OUE Hospitality Trust Chong Kee Hiong.

Said Mr Chong, 49: "He has left me a huge pair of shoes to fill."

Before leaving the Cabinet in 2011, Mr Wong held various positions, including home affairs minister from 1994 to 2010 and deputy prime minister from 2005 to 2011.

With his retirement, Prime Minister Lee Hsien Loong would be the only one from the 1984 group still in politics.

Referring to the PAP's policy of self-renewal, Mr Wong said: "I'm doing my part now to find people who will succeed me... to carry on the work the PAP started in 1959."

He thanked residents and grassroots leaders for their support.

As for Mr Nair, Dr Ng praised the quality of his contributions in Parliament: "Many of us, including myself, are always impressed with his stirring and piercing speeches."

Mr Nair said: "I have never held back. The ministers don't always agree with me but they've always respected my right to speak up and to say what I want to say."

The senior counsel is chairman of the Government Parliamentary Committee for Law and Home Affairs. He spoke for the first time in public about his wife's battle with cancer of the lymph nodes.

It was diagnosed in 2012 and while she is doing well now, the condition "is not the sort of thing that really goes away", he said.

"I've had to refocus my priorities,'' he said.

He is looking forward to spending more time with his wife and his eight-year-old daughter.

"She's a great little girl. I'm looking forward to spending more time at home annoying her, which is what she accuses me of doing all the time," he said of his only child.

The two-term MP has been chairman of the Bishan-Toa Payoh Town Council since 2011, a position he will relinquish when Parliament dissolves ahead of the polls.

He added that he was proud of the town council's record and its rating as one of the best here.

Mr Zainudin was the town council's immediate past chairman and former central district mayor. He was also chairman of Onepeople.sg, a national body focused on promoting racial and religious harmony, from 2007 to 2011.

A three-term MP, he is known for championing the cause of the less privileged. "As a party, as a team, we have always been very clear. We need to continue to serve, to develop the people.

He said: "I'd like to say 'thank you' to all the residents of Bishan-Toa Payoh GRC, and of course the Malay-Muslim community in Singapore, for giving me the opportunity to serve."