Minister in the Prime Minister's Office Chan Chun Sing said yesterday that having an election after the end of President Tony Tan Keng Yam's term is not unconstitutional.

Law professor Kevin Tan had cited Article 17(b) of the Constitution, which says that if there is a sitting president, an election cannot be held more than three months before his term expires. Prof Tan took this to mean that an election held after the end of a sitting president's term is unconstitutional.

Dr Tan's term ended on Aug 31, before the Sept 23 election. Council of Presidential Advisers chairman J.Y. Pillay is the Acting President.

Mr Chan replied: "It is not that you must hold it within three months before the end of term. You cannot hold it more than three months before the end of term."

This is meant to prevent the Government from prematurely turfing out a president and making him a lame duck, said Mr Chan. He added that this year's delay was a "one- time reset" to prevent the campaign clashing with National Day festivities. Parliament's support for the move was also sought and received.

Charissa Yong