Singapore is a republic with a parliamentary system of Government based on the Westminster Model. The Constitution of the Republic of Singapore provides for a President who is the Head of State. Prior to 1991, the President was appointed by Parliament and had a largely ceremonial role.

In January 1991, the Constitution was amended to allow for the election of a President by the citizens of Singapore. The elected President will hold office for a fixed term of six years. The creation of the elected presidency is a major constitutional and political change in Singapore's history. The elected President has the responsibility under the Constitution to safeguard the national reserves and the integrity of the public service in Singapore.

Under the revision, the President is empowered to veto government budgets and key appointments to public office.  The President must, however, consult the Council of Presidential Advisers before he takes a decision on some of these matters.

The first Presidential election was held on 28 August 1993. Mr Ong Teng Cheong was elected, and he served a six-year term from 1 September 1993 to 31 August 1999.

Mr S R Nathan became the second Elected President on 1 September 1999. On 17 August 2005, he was re-elected and was sworn-in for his second term of office on 1 September 2005