Main reason for this GE is the gerrymandering + fearmongering due to tariffs.
He did not go bad in parliament.
I think the New Citizens (due to XJP turning China into a dictatorship during the last 5 years) translated into a lot of votes for PAP.
New citizens every election also have and they are all dispersed everywhere, it makes less of an impact than you might think. The main factor is Trump tariffs creating a period of uncertainty. You have to thank Trump for PAP winning
