Six MPs are helping Dr Koh Poh Koon canvass for votes this weekend, fanning out with fliers and greeting residents.
Some went out on their own yesterday while Dr Koh continued to walk the ground alone as he had done in the days before.
Dr Koh began his morning greeted by the Prime Minister who joined him at a party branch office for a breakfast of porridge, before both men set out separately to meet residents.
Mr Lee Hsien Loong, making his first entry into the campaign since he called the by-election, went with helpers to Rivervale Plaza while Dr Koh started his walkabout around the ward.
Asked why he did not accompany Mr Lee, the candidate said: "My focus has always been to reach out to residents personally. He is here to give us support and encouragement as activists from the branch.
"So while he is doing his encouragement, I'm continuing my hard work on the ground going from block to block, house to house, to do the visits."
In the intermittent rain, Dr Koh spent the day meeting residents and handing out fliers. He also inspected the pedestrian walkway outside Rivervale Plaza known to be covered with water when rainfall is heavy.
Over there, he cleared the leaves that had blocked the drainage for rainwater.
Even as he did this, MPs Zaqy Mohamad (Chua Chu Kang GRC), Baey Yam Keng (Tampines GRC) and Charles Chong (Joo Chiat) fanned out with activists to knock on doors yesterday.
A group of about 20 Young PAP members from different constituencies also gave out fliers at Rivervale Mall in the afternoon.
MPs from the adjacent Pasir Ris-Punggol GRC Janil Puthu-cheary, Zainal Sapari and Gan Thiam Poh are due to pitch in today.
Asked about their involvement now and not earlier, Dr Koh said: "They are part of the wider network of the party and I think they have been really itching to try and pitch in and do their part as well."
Speaking to The Sunday Times, Mr Zaqy said he was supporting a "brother" and to supply "additional firepower".
Dr Koh has five more days to cover as many of the 127 Housing Board blocks in the ward as possible, before Cooling-Off Day this Friday.
Punggol East used to be in the Pasir Ris-Punggol GRC. It was carved out as a single-seat constituency in the 2011 General Election. Under former Speaker of Parliament Michael Palmer, the ward was kept under the same town council management.
Separately, at the launch of grassroots centre One Connect at Bishan-Toa Payoh GRC, Defence Minister Ng Eng Hen said that Singaporeans were happy that the campaign is being conducted cordially, with dignity and decorum and among credible candidates.
"I hope that tone of the campaign can be continued."