SINGAPORE, July 18 — Once touted as an up-and-coming member of the ruling party’s fourth generation (4G) of leaders, Tan Chuan-Jin has resigned as Speaker of Parliament, Member of Parliament (MP) and member of the People Action’s Party (PAP) over his personal conduct.

Prime Minister Lee Hsien Loong said yesterday that he had accepted Tan’s resignation in February, but had wanted to ensure that Tan’s Marine Parade Group Representation Constituency (GRC) residents were taken care of.

In a letter to Tan, Lee said: "I appreciate your admission that you have fallen short in the matter of your personal conduct, and understand your desire to step away from politics and help heal your family.”

Before the latest controversy became public, Tan had apologised to a Workers’ Party MP for using unparliamentary language during an April sitting of Parliament.

Tan’s resignation came together with that of fellow PAP member Cheng Li Hui, Tampines GRC MP. Lee said the pair had been involved in an "inappropriate relationship”.

Lee said that it "saddens me” that the two MPs had fallen short of the high standard of propriety and personal conduct that we expect from all MPs” but that it was necessary to maintain these high party standards.

"This means to counsel, to correct, to admonish, and ultimately, if necessary, to remove the MP from the party and Parliament.”

Here is a look back at the careers of Tan, 54, and Cheng, 46.

From career soldier to fast-track minister

Prior to joining politics in 2011, Tan was a career soldier for about 24 years in the Singapore Armed Forces (SAF), where he rose to the rank of Brigadier-General.

One of his notable achievements was leading the relief efforts to Aceh, Indonesia in the wake of the 2004 tsunami. The relief mission remains one of the SAF’s largest military operations to date, according to Tan’s curriculum vitae on the Parliament website.

In May 2011, he was elected as an MP as part of the Marine Parade GRC team led by party stalwart Goh Chok Tong. Tan has remained MP for the Kembangan-Chai Chee ward since then.

Two weeks after the 2011 General Election, he was appointed a Minister of State at the Ministry of Manpower and Ministry of National Development.

He became Acting Manpower Minister in 2012, and a full minister in 2014. About a year later, he became Minister for Social and Family Development. — TODAY