For the past two years, they have vociferously championed topics ranging from the arts to the income gap, the plight of small and medium-sized businesses, and women in the workforce.
But a touch of wistfulness descended on four Nominated MPs when a marathon nine-day parliamentary sitting ended on Thursday.
It will be the last Budget and Committee of Supply debates for Mr Teo Siong Seng, Mr Laurence Lien, Ms Janice Koh and Ms Mary Liew, who will not seek an extension of their 21/2-year terms when they end in August.
All four pointed to a need for fresh voices in the House.
Ms Liew will remember with fondness her maiden speech in February 2012, when she pushed for a restoration of Central Provident Fund (CPF) contributions for older workers, as many had insufficient savings in their accounts for retirement.
During his Budget statement last month, Deputy Prime Minister Tharman Shanmugaratnam said rates for workers aged above 50 to 55 will be raised from 32.5 per cent to 35 per cent, and those above 55 to 60 from 23.5 per cent to 25 per cent, from January.
Ms Liew, the general secretary of the Singapore Maritime Officers' Union, has also pushed for better pay for cleaners and security officers.
In recent months, the Government has moved to implement a progressive wage model in both industries.
"I am certainly more than glad that the Government took notice of some of the issues I raised together with my fellow labour MPs," she said.
"But more importantly, that these new policies will indeed be helping those who need them the most."
Meanwhile, Mr Teo, who is vice-chairman of the Singapore Business Federation, said his NMP stint was both challenging and rewarding, and he is particularly happy about how he had fought for the concerns of small businesses.
Over the past few years, he said, they had felt left out of policies such as the Productivity and Innovation Credit scheme, which aims to help companies restructure.
Ms Koh, meanwhile, has tirelessly pushed for greater support for local artists, further promotion of the study of literature in schools and a shift in focus from rote learning.
"It has been a privilege to serve, but the arts and culture sector is a diverse one, and others should be given the opportunity to bring their views to the table," she said.
Mr Lien also felt it would be appropriate to pass on the baton to another leader in the social arena. The National Volunteer and Philanthropy Centre (NVPC) chief executive has spoken on the need to support vulnerable groups such as the poor, elderly and the disabled.
The four who are stepping down were among nine non-partisan individuals appointed as NMPs in February 2012. Some NMPs have been known to stay up to three terms in the past.
The other five - businessman R. Dhinakaran, university don Eugene Tan, polytechnic lecturer Faizah Jamal, Singapore Institute of International Affairs executive director Nicholas Fang and DBS' head of wealth management Tan Su Shan - remain undecided on whether they will seek an extension.
But in making her decision, Ms Tan is mindful that the NMP system - set up in 1990 to provide alternative voices in Parliament - plays an important role in the House.
"The whole reason we are there is that we don't need to please any constituency. We can voice out what is unpalatable in the short term, but good for Singapore in the long term."
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