Opposition parties have resolved remaining differences and are set to go into straight fights with the ruling People's Action Party (PAP) at the next general election.
This follows announcements yesterday by the National Solidarity Party (NSP) and Singaporeans First party (SingFirst) to withdraw from areas other opposition parties have also staked claims to.
Opposition party leaders have spoken about the need for unity that has often proven elusive in recent years, and the avoidance of three-cornered fights which they see as favourable to the PAP.
NSP acting secretary-general Hazel Poa reiterated this when announcing it would stay out of Marine Parade GRC and the MacPherson single seat - both also claimed by the Workers' Party (WP).
She said the party was doing so to avoid diluting the opposition vote and reducing the chances of a more diverse Parliament.
SingFirst made a brief statement about its withdrawal from Ang Mo Kio GRC, first claimed by the Reform Party (RP).
Both moves pave the way for straight fights between the opposition and ruling PAP in all 29 constituencies - although independents could join the fray.
Ms Poa expressed disappointment that the NSP had to cede constituencies where it had walked the ground and said it was a "difficult decision" to make.
But it recognised "voters' desire for greater opposition representation in Parliament", she said.
WP chairman Sylvia Lim responded by thanking the NSP. In a statement, she also said the WP "will continue to focus on its preparations and campaign on the 10 constituencies announced".
Both parties had stood firm over Marine Parade during all-party opposition talks last week.
The WP offered to give up MacPherson if the NSP stayed out of Marine Parade, but this was rejected, said Ms Lim last Friday.
But Ms Poa said yesterday that the NSP informed the WP in an e-mail on the same day of its decision to pull out. It hoped to issue a joint statement on this "as a symbol of cooperation" but the WP did not respond.
She also lamented the WP's no-show at the second round of talks opposition parties had last Thursday, saying the issue could have been settled then.
Opposition parties met twice last week - the first time on Monday - to discuss constituencies and contests. The WP was a no-show on Thursday, saying that it had already made its intentions clear.
Said Ms Poa yesterday: "As there are many who are anxious for an outcome, NSP decided not to delay any further, but to make this announcement on our own."
The party will now contest in Tampines and Sembawang GRCs and the Pioneer single-seat ward.
Ms Poa thanked the Singapore Democratic Party for "voluntarily withdrawing from Sembawang GRC in the interest of opposition unity".
Another potential three-cornered fight in Ang Mo Kio GRC, which is helmed by Prime Minister Lee Hsien Loong, was also averted after SingFirst secretary-general Tan Jee Say's pledge not to contest there. His party will focus on Tanjong Pagar and Jurong GRCs.
The RP yesterday had a walkabout in Ang Mo Kio with blogger Roy Ngerng and lawyer M. Ravi, who said previously that he wanted to contest the next election in the GRC.
But three-cornered fights do remain a possibility as lawyer and former NSP chief Tan Lam Siong has said he will run in Potong Pasir - claimed by the Singapore People's Party - while former independent candidate Ooi Boon Ewe told reporters last week he intends to stand in Sengkang West, which the WP will contest.