SINGAPORE (AP) — Singapore’s Prime Minister Lee Hsien Loong will stay on in the government as senior minister after he steps down next month, his successor said Tuesday.

Lee, 72, announced Monday that he will end his 20-year rule and hand over to his deputy Lawrence Wong on May 15.

Lee is the eldest son of Lee Kuan Yew, Singapore’s first prime minister who built the resource-poor city-state into one of the world’s richest nations during 31 years in office.

Wong will be Singapore’s fourth leader since independence in 1965. The transition has been carefully crafted in the wealthy city-state known for its tight government control, media censorship and use of oppressive laws against dissidents.

Wong, who is also finance minister, credited Lee for Singapore’s strong economic growth and said he was glad that he agreed to stay on as senior minister. former Prime Ministers Lee Kuan Yew and Goh Chok Tong had also served as senior ministers after stepping down.