A presidential election to find a Head of State to unite Singaporeans has ended up splitting the electorate.

And a lot of effort is needed to close up the deep division, said Dr Tan Cheng Bock who lost by a razor-thin margin of 0.34 per cent against Dr Tony Tan, who captured 35.19 per cent of votes and is Singapore's seventh President.

Speaking to the media at his home, Dr Tan Cheng Bock said: "You see, you must never run away from the issue. If it's divisive, you can't say oh cannot do. All the more you have to make the effort. That will make people wake up to have that aim for the whole of Singapore."

Dr Tan told reporters that the new President-elect will have to re-examine the focus of his six-year presidency.

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"You have to watch over the couple of months how he's going to convince the other 65 per cent who didn't vote for him. Knowing that his strength is in the economy, he has to put some effort into the ground, because you can't just look after the external area - you have to concentrate on your people."

Dr Tan, who was a member of PAP until May this year, also said that the ruling party needs to take a good hard look at itself.

"There's definitely a division in the PAP. I can see many of the grassroots openly come and tell me they support me in spite of being told by others not to. They obviously abandoned that expected stand and it's reflected in the votes. The PAP split is right down in the middle. But I'm no longer in PAP.

"The party will need to take a critical look at their own way of doing things. They have to learn how to fight again. They have lost their fighting skills. They must learn from me." His comment was greeted with laughs from around the room.

Dr Tan said he will not return to the PAP but he will give advice to the party if his advice is sought.