For all the predictability of elections in Singapore, one result will be keenly watched when the city-state votes on Friday as Finance Minister Heng Swee Keat must win an unsafe seat to show people he has what it takes to be a future leader.

Promoted last year to deputy prime minister, 59-year-old Heng is in line to succeed Lee Hsien Loong, as the son of Singapore’s modern founder Lee Kuan Yew has said he will step down in coming years.