"Presidential elections are generally open to candidates of all races but if we have not had a president from a particular community for five consecutive terms, then the next term will be reserved for candidates from that community. If one of them is elected, we will have a president from that community, " Lee declared in Parliament.
Singapore's first president, Yusof Ishak, who served from 1965-1970, was Malay but he was appointed to his post. Before laws were introduced in 1991 that changed the selection of the president to a public poll, leaders were chosen by Parliament.
Three of the four Presidents since 1991 have been of Chinese heritage, including current head of state Tony Tan Keng Yam, who announced on Tuesday that he would not seek a second term.
Under the new amendments, there will be at least one Chinese, one Malay, and one president who is either Indian or "other minority" within the course of six presidential terms, provided qualified candidates appear.
"So if a Malay candidate steps up to run, or more than one Malay candidate step up to run, who is qualified, Singapore will have a Malay president again," PM Lee said.
He acknowledged that some may knock this arrangement for going against the principle of meritocracy, but he said critics should consider two key points.
The candidate in a reserved election would be required to meet the same qualifying criteria, i.e."be as qualified as any other candidate who stands and wins in a non-reserved election," he said. Moreover, the new model would ensure a mix of different races over time, he added.