Over the past nine days, Progress Singapore Party (PSP) chief Tan Cheng Bock has hit the campaign trail hard across the island.

He has joined walkabouts from Nee Soon to Tanjong Pagar, and seemed to have graced more events outside West Coast GRC, where he is standing for election.

Although Dr Tan wrapped up his campaign in West Coast GRC yesterday, he is set to be the party leader who has campaigned in the most number of constituencies in this election.

Political observers said this is part of a strategy by Dr Tan to elevate his campaign to the national level, while continuing to shine a spotlight on his West Coast campaign. They note, however, that it can be risky.

Singapore Management University law don Eugene Tan said: "It can be double-edged. If voters feel he is not paying enough attention, then it will backfire on him.

"This strategy to galvanise and rally support for the opposition as a whole, rather than running a localised campaign, is counter-intuitive."

Despite being one of the newest parties, the PSP is contesting 24 seats, including in Chua Chu Kang, Tanjong Pagar and Nee Soon GRCs, and the single-seat constituencies of Marymount, Pioneer, Yio Chu Kang, Kebun Baru and Hong Kah North.

Dr Tan kicked off his election campaign in West Coast GRC on Tuesday last week, when he and his team headed to Ayer Rajah Food Centre for a lunchtime walkabout after filing their papers on Nomination Day.

The next time the media saw him in the constituency was on the weekend, when the five-man West Coast GRC team hit the three biggest markets in the area.

Since then, Dr Tan has gone on walkabouts mostly outside West Coast GRC.

On Sunday, he was walking with his entourage and party member Lee Hsien Yang - who is not contesting - in Nee Soon GRC. On Tuesday, he was in Tanjong Pagar GRC.

Meanwhile, the PSP team for West Coast GRC has been conducting market visits without its star attraction.

On two occasions this week, he appeared with candidates from other parties, saying he was there to support his friends.

On Monday, Dr Tan was in Elias Road in Pasir Ris-Punggol GRC to support the Singapore Democratic Alliance team, which is contesting there for the fourth time since 2006.

Then on Tuesday morning, Dr Tan held a joint walkabout with Singapore Democratic Party chairman Paul Tambyah at a coffee shop in Bukit Panjang SMC, where Prof Tambyah is contesting.

Dr Felix Tan, associate lecturer at SIM Global Education, said Dr Tan is trying to bring more attention to the opposition candidates, not just those from the PSP.

"He knows his strength is that people notice him. People will probably listen to him, and so his support of the other opposition parties is notable.

He added that the PSP chief is an "old-school politician", who comes from an era where instead of just online presence, there was a big focus on walkabouts and showing of physical presence.

"When he meets the other candidates and parties, he helps them get more airtime in the media, as some of them may otherwise get overshadowed by their PAP (People's Action Party) opponents."

Associate Professor Eugene Tan agreed, saying: "These party leaders take it upon themselves to not be confined to the ward they are contesting in. They see campaigning at the national level as helping their overall campaign effort."

He added, noting that gaining a national profile could help Dr Tan in his own constituency: "Some might say there's a degree of conceit in him (Dr Tan), that he's taking the fight to the PAP even in areas he is not contesting in... But there is a method in that seeming madness."

Asked about his walkabouts outside West Coast GRC, Dr Tan said it should not be taken as a sign he thinks he has the constituency in the bag.

"No, no, no. We never take (victory) for granted." he said last Friday. "I am the leader, so I must support all my candidates."