People have always come before party colours for presidential hopeful Halimah Yacob, who said at a press conference yesterday - to unveil her campaign slogan - that her close ties to the ruling party will not affect her ability to act independently as president.

The long-time People's Action Party MP, who left her political and party posts earlier this month to run in the presidential election, said: "Whatever I do, it must always be the people first, and the people first, and the people first."

"And if, as a candidate, at any time, I feel that I am not able to be independent, I would not offer myself," she added, a day after the Writ of Election was issued.

Madam Halimah was speaking at the NTUC Centre where she announced her slogan, "Do Good Do Together", and introduced some members of her campaign team.

She also fielded questions from reporters ranging from whether she could truly be independent, to whether a walkover may impact her legitimacy as president.

Since the former Speaker of Parliament announced her presidential bid, she has sought to convince Singaporeans that her past political affiliations will not compromise her independence.

Pointing to her long years in public service - she spent more than two decades in the labour movement before joining politics in 2001 - she said she has always placed the interests of the people first.

She added that it will be "a gross disservice" to do otherwise.

She cited former president Ong Teng Cheong as a PAP politician- turned-president who did not always agree with the Government and established for himself the reputation of "the people's president".

"Every day, we get up, we have to look at ourselves and ask ourselves, who are we serving? I have asked myself that question and I know where my loyalty lies. My loyalty lies with Singapore and Singaporeans, and nothing else," she said, adding that she has, during her time in the unions and in politics, disagreed with the Government.

Singaporeans will vote in the first presidential election reserved for Malay candidates on Sept 23, if more than one person qualifies to run for the position.

Madam Halimah is the only one among the three aspiring candidates who automatically qualifies, having served as Speaker of Parliament for more than three years.

Whether the other two candidates will qualify will depend on the discretion of the Presidential Elections Committee, which assesses candidates for eligibility.

Asked if she would worry about her legitimacy as president if she won in a walkover, she said: "This is a democratic process... Eligibility criteria are transparent."

Law don Simon Tay, who was at the press conference as one of Madam Halimah's nominators, pointed out that former president S R Nathan twice became president in a walkover, after other prospective candidates were found ineligible.

"At the end of his two terms, President Nathan had erased any question mark over his presidency," he said. "I think history has borne out that Singaporeans recognise a good president when they have one."

Madam Halimah, who has fought and won four general elections, added that she would be prepared whether the election turns out to be a two- or three-cornered fight.

She is expected to submit her application forms to run in the election today.

On whether she would prefer to contest in an election open to candidates of all races, she said "the requirements are the same" for both reserved and open elections.

The principle of meritocracy "is not undermined in any way" in a reserved election because all candidates who take part must still meet the various qualification criteria, she added.

Madam Halimah said she would contest in an open election, but stressed that being elected in a reserved election would not affect her ability to perform her duties.

She also said she hopes a president elected through a reserved election would be seen as someone who represents all Singaporeans.

While Singapore has had success in promoting harmony among the different races, she said, there was still a way to go before race becomes a non-issue at elections.

"At some point, I do hope that in future we may not need a reserved election... but I think the process is still a work in progress. And I really hope that this is how we will look at this reserved election," she said.