"The most important thing is to ascertain if opposition presence in parliament has grown," observer Terence Chong, from the Iseas-Yusof Ishak Institute, explained.

The current make-up is 80-7, with all seven minority seats held by the Workers' Party (WP). It is an outfit set up in 1957 to agitate against British colonial rule, not unlike the PAP.

The WP made a breakthrough in the last general election in 2011, winning one of the multi-seat wards for the first time.

These Group Representation Constituencies (GRC) were seen as strongholds of the PAP and usually led by a cabinet minister or two. That defeat four years ago led to the ruling party losing three ministers. The question is whether the WP can build on that breakthrough.

"It will be an indicator of whether Singapore's evolution into a normal democracy is gaining speed or is the one-party dominance still resilient even in a post-Lee Kuan Yew era," said observer Eugene Tan from the Singapore Management University.

If the WP can win another GRC, it will be a serious blow to the ruling party, observers said.

"The loss of a second GRC, despite the SG50 jubilee celebrations and the emotions of LKY's passing, can only be treated as a major rebuff for the PAP," said observer Cherian George of Hong Kong Baptist University in a blog post. He was referring to Singapore's 50th year of independence, celebrated last month.

Another GRC defeat would also mean the loss of more ministers. This comes after an election campaign where the PAP's leader, Prime Minister Lee Hsien Loong, had asked for support so he could put a new team of leaders in place.

"In the PAP team we are renewing our slate and presenting new candidates, and reinforcing our team with potential office holders to strengthen the leadership, to form the next generation of leaders that will take over [from] me and my team," the son of the late Lee Kuan Yew said last month.

In Singapore, leadership in the PAP, and by extension the country, has been categorised by generation, in a similar fashion to China. The founding leaders led by Lee Kuan Yew are regarded as the first generation, followed by Goh Chok Tong's second generation and Lee Hsien Loong's third. The next batch, expected to take over within the decade, is referred to as the "fourth-generation", or 4G, leadership.

"The core of the 4G leadership, comprising MPs in their 40s and early 50s, will take shape more concretely after the election," said Tan. "Perhaps the successor to PM Lee will be clearer midway through the term of the next parliament."

Erosion of the PAP's presence in the legislature would force the ruling party to re-examine policies which drew fire during the short-lived campaign.

Its openness to foreigners remains emotive and divisive. If the PAP finishes today with fewer seats and a lower vote share, down from the previous 60.1 per cent, it may be forced to further calibrate its immigration policies.

Such practical issues, said Chong, would preoccupy the minds of swing voters. Others would consider more philo-sophical concerns on the state of Singapore's political system, he said.

"Should they trust a ruling party that has proven itself competent and honest, or help nurture a credible opposition party for the long-term health of national politics?"