On 17 July 2023, Cheng and Tan Chuan-Jin simultaneously resigned from all their positions in the government and as members of the PAP due to "propriety and personal conduct", alluding to adultery.[6] In a statement, Prime Minister Lee responded to their resignation letters that their resignations were "necessary" to "to maintain the high standards of propriety and personal conduct which the PAP has upheld all these years."[7][8] Their respective seats at Marine Parade GRC and Tampines GRC was subsequently left vacant, including the workload for the Kembangan–Chai Chee division in the case of Tan and Tampines East division in the case of Cheng distributed among the other MPs in their respective GRCs.