The position of Senior Minister has only been held by four persons -- Lee Kuan Yew and Goh Chok Tong, who were the first and second Prime Ministers of Singapore respectively; and S. Rajaratnam and S. Jayakumar, who served as Deputy Prime Ministers.
Despite speculations that former Senior Minister S. Jayakumar was considering a run, he stated that he would not be running in an interview.