SINGAPORE - The ruling PAP is likely to be challenged in all 93 seats by 10 opposition parties at the close of nomination proceedings on Tuesday (June 30).

Follow our live coverage on Nomination Day as the parties unveil their final line-ups for the general election.

Here are five things to look out for:

1. Who will helm the People's Action Party team in East Coast GRC?

For the PAP's East Coast team, this year's general election marks the end of an era.

Mr Lim Swee Say, the group representation constituency's anchor minister, is set to retire. But the identity of his successor is perhaps the party's best-kept secret so far.

Political analysts have tossed up several possibilities - one option could be for either Deputy Prime Minister Heng Swee Keat or Minister for the Environment and Water Resources Masagos Zulkifli to move over from Tampines GRC, which shares a boundary with East Coast.

There is also speculation over whether Minister for Social and Family Development Desmond Lee, who will be leaving Jurong GRC, could be fielded in East Coast GRC.

Other watchers point to the possibility of a heavyweight like Senior Minister Teo Chee Hean, the anchor minister for Pasir Ris-Punggol GRC, being moved over. What the PAP will eventually decide on, however, is still anyone's guess.

2. Who will be in the Workers' Party lineup for East Coast GRC and Punggol West SMC?

The Workers' Party's East Coast slate from the last general election will not be making a comeback this year. Associate Professor Daniel Goh has dropped out of the running, citing health reasons. Mr Leon Perera and Mr Gerald Giam will move to contest as part of the WP's Aljunied GRC team instead.

It remains unclear who the WP has decided to field in East Coast, which saw the closest contest in the 2011 general election when the PAP won with 54.8 per cent of the vote. In 2015, the PAP secured 60.7 per cent of the votes against the WP.

Another question is which WP candidate will contest the newly-created single seat of Punggol West, which is near SMCs that the party previously contested.

The party had put up a tough fight for Sengkang West and Punggol East SMCs, both of which have been taken into the new Sengkang GRC.

The PAP won Punggol East by a slim margin in 2015 when party stalwart Charles Chong took the single-member constituency from the WP's Ms Lee Li Lian, with 51.76 per cent of the vote. She had won the SMC in a 2013 by-election.

In 2015, Dr Lam Pin Min of Sengkang West SMC also defeated his WP opponent Koh Choong Yong with 62.1 per cent of the vote.

3. How many multi-cornered fights will there be?

Opposition parties will be heading to the polls without having had their usual pow-wow to avoid three-cornered fights. Instead, parties held discussions with one another directly or in small groups - a process that has so far produced mixed results.

Multi-cornered fights are expected to take place in at least three constituencies - Pasir-Ris Punggol GRC and the single seats of Pioneer and Punggol West. But more could emerge if independent candidates decide to toss their hats into the ring as well.

Retired financial accountant Victor Ronnie Lai, 65, has already declared his intention to run as a candidate in Pioneer, raising the prospect of a four-way fight there.

Last week, Mr Ooi Boon Ewe, 79, was also seen picking up nomination papers at the Elections Department. Mr Ooi has attempted to run in multiple elections as an independent, and told reporters that he intends to contest Bukit Panjang SMC.

4. Will Mr Lee Hsien Yang stand for election?

Mr Lee Hsien Yang, the 62-year-old estranged brother of Prime Minister Lee Hsien Loong, is currently a member of the Progress Singapore Party (PSP) led by Dr Tan Cheng Bock.

He has also been accompanying the party's members on their walkabouts.

But Mr Lee was not among the slate of 24 candidates introduced by the PSP last week.

Even so, Dr Tan reminded reporters last Friday that the party's lineup could still change. "Candidates can be switched all around so you will have to just wait and see," he said.

5. How will the Covid-19 pandemic affect Nomination Day proceedings?

With entry into nomination centres restricted due to the Covid-19 pandemic, this year's Nomination Day is likely to be a much more subdued affair.

Only candidates, their proposers, seconders, assentors and accredited media can enter nomination centres. Party supporters will not be allowed to linger nearby, putting an end to the large crowds typically seen on Nomination Day.

Candidates who are unwell also do not have to be present at the nomination centres on Nomination Day. Instead, they can authorise a representative to file the nomination papers on their behalf.

Reform Party secretary-general Kenneth Jeyaretnam, 61, will require a representative to file his papers. He recently returned to Singapore from the United Kingdom, and will be serving his 14-day stay-home-notice on Nomination Day. He had asked for a waiver but was rejected for public health reasons.