Singapore has managed to become an exceptional country because it has kept its system of government clean, said Prime Minister Lee Hsien Loong.
"Singapore is special, and is able to stay special, because we have a clean system," he said. "To have a clean system, you must have people who are trustworthy, who are honest, who you can rely upon and who will not be saying one thing, doing another or putting their hands into their kitty."
To keep it this way, voters should assess candidates from different parties for their integrity of character, he argued.
Taking up the point, Dr Ng Eng Hen, organising secretary of the People's Action Party (PAP), said the party will not field as its candidate anyone found skirting too close to unethical boundaries or running for office for personal gain. This is because the party expects high standards of integrity from its candidates and MPs, he said, adding that other parties should aim for the same as well.
"The PAP is the harshest critic for our own candidates," he said at a press conference at the party's headquarters in Bedok yesterday.
Dr Ng, who has been screening PAP candidates for the past 10 years, said senior party leaders grill potential candidates on their motivation for entering politics.
"We ask probing questions. Why are you in it? Are you self-serving? Are you doing this for gain? You'd be put into positions where you can benefit," he said of the process, which he described as onerous.
The final batch fielded at each election is whittled down from 300 to 400 people for each selection round.
They go through several cycles involving senior members of the party and, finally, PM Lee, the PAP's secretary-general.
Dr Ng said: "If there is any doubt that a candidate is running for office because he or she wants to be in a position to benefit personally from holding office, they will not be fielded."
Even after they get into Parliament, these standards apply.
"We've dropped MPs and called fresh elections when they don't measure up, even when we take losses," Dr Ng added, in a clear reference to former Speaker of Parliament Michael Palmer's resignation in 2012 over an extramarital affair.
His vacated Punggol East seat was won by the Workers' Party's candidate, Ms Lee Li Lian, in the subsequent by-election.
Dr Ng recounted how the late founding prime minister Lee Kuan Yew, on his 90th birthday in 2013, had said that Singapore must remain clean and incorruptible and exhorted MPs to set that example.
"I think he understood that this is a very strong and strict moral fibre that you don't weaken. Because, if you do, Singapore will be weaker for the future," said Dr Ng.
This is why the PAP was pressing the issue of character, even though it was neither a strong nor popular political platform.
"We think it's necessary just to say, gently, that all of us must do our part to make sure that we keep Singapore the way it is, and to keep very high standards for all of us," he said.