Workers' Party candidate Lee Li Lian says she is all ready for the battle.

Speaking to reporters after she was successfully nominated, Ms Lee said she plans to cover all the blocks in Punggol East over the nine-day campaign. She has started a Facebook page for the by-election but said that nothing beats the personal touch and getting to meet residents at walkabouts and house visits.

Ms Lee, 34, reiterated her intention to raise issues close to the heart of young couples and families, such as the cost of living and housing and the stressful education system.

Asked how she felt about the four cornered fight, she said in Mandarin, "With a calm heart."

The WP has said that they respect all parties' right to contest. Workers' Party chairman Sylvia Lim said her party would remain focused on their own campaign, regardless of the number of candidates contesting.

She was speaking to reporters outside the nomination centre, after it was announced that the Punggol East race had officially become a four-cornered fight.

Asked what issues WP would be raising during the campaign, she said: "We won't want to commit on issues now, because things can change very fast during the campaign."

WP MP from Aljunied GRC Chen Show Mao added that the party would work hard to meet every constituent during the campaign, to ask them to vote for his party.

He added that electing Ms Lee Li Lian of WP would mark another step forward in Singapore's democratic development.

Ms Lee had fought in the ward in a three-cornered fight in the 2011 general election. She won 41 per cent of valid votes then.