The last to decide, Nominated Member of Parliament (NMP) Nicholas Fang, 38, said on Tuesday afternoon he would not be seeking a second term.
The Singapore Institute of International Affairs executive director said he is stepping down to concentrate on his duties as chef de mission for Singapore at next year's SEA Games, which will be held here.
"I want to focus all my energies on making sure that we do all that is needed to deliver the best possible result for Team Singapore in 2015," he said.
Mr Fang is among the nine non-partisan politicians who will leave Parliament in August when their two-and-a-half-year term ends.
Only two of them will seek a second term. They are university don Eugene Tan and businessman R. Dhinakaran.
Meanwhile, two names have come up as potential candidates for the next group of NMPs.
The labour movement is proposing veteran union leader K. Karthikeyan while artistic director Kok Heng Leun wants to represent the arts, media and sports sector.
The NMP scheme was launched in 1990 to have more alternative voices in Parliament.
NMPs represent seven sectors in the House: business and industry; the professions; the labour movement; social service organisations; the civic and people sector; tertiary education institutions; and the arts, media and sports.
The public has until May 20 to propose individuals they deem suitable. The President will make the final decision.