SINGAPORE (Reuters) - Singapore Prime Minister Lee Hsien Loong reshuffled his cabinet on Tuesday, naming one of his potential successors, Chan Chun Sing, as trade minister and giving additional duties to two other ministers tipped as contenders.

Singapore's Prime Minister Lee Hsien Loong speaks with Chinese Vice President Wang Qishan(not pictured) during their meeting on April 9, 2018 at the Zhongnanhai Leadership Compound in Beijing, China. Parker Song/Pool via Reuters

Lee, the eldest son of Singapore’s founding father Lee Kuan Yew, has made clear he is ready to stand down in the next couple of years, but no obvious successor has emerged from a group of 16 ministers tasked with picking a leader from within their ranks.

Chan is one of three potential successors touted by Singapore’s media and political analysts, alongside Finance Minister Heng Swee Keat and Education Minister Ong Ye Kung.

The People’s Action Party has ruled the island-state since its independence more than 50 years ago, and there have been only three prime ministers.

Singapore’s next general election is due by early 2021.

“The leadership transition taking place in the next few years is well underway,” the prime minister said in a Facebook post after the reshuffle.

“The younger ministers will progressively take over more responsibility for governing Singapore,” he said.

Chan, previously a minister without portfolio, becomes trade minister and also assumes responsibility for the civil service, known as the Public Service Division, from Deputy Prime Minister Teo Chee Hean.

Heng, who keeps the finance post, will also assist the prime minister on matters related to the National Research Foundation -- a research and development arm of the Prime Minister’s Office. That role was previously held by Teo.

Ong becomes the sole education minister, a role he previously shared with Ng Chee Meng, who was appointed minister in the Prime Minister’s office.

Gillian Koh, deputy director of Research at the Institute of Public Policy Studies, said that Chan and Heng’s roles are in “very heavyweight ministries”.

“The wonder is whether Mr. Ong is sliding or in a position that keeps him on track to be in contention,” Koh said, adding, “the game is still afoot”.

The reshuffle did not name any new deputy prime ministers, which are currently held by Teo and Tharman Shanmugaratnam.

But Eugene Tan, an academic and former nominated member of parliament, said the reshuffle seemed to give Chan “a slight edge” in the race to replace Lee.

Tan said Chan’s additional responsibilities over the civil service, as well as diverse experience in other ministries and responsibility for a governmental initiative with China, gave him an advantage over the others.