The elected president must be able to work with the government of the day so that Singapore can function effectively, said President Tony Tan Keng Yam yesterday in his first comments on the proposed changes to the office.

The president also plays the key roles of being a symbol of national unity and a custodian of Singapore's treasured assets, said Dr Tan.

But while the elected president plays a custodial role, he cannot be a second centre of power, Dr Tan added as he set the tone and implicit parameters for the MPs' debate.

His comments were read in Parliament by Speaker Halimah Yacob at the beginning of a three-day debate on amendments to the Constitution, following a landmark review of the 25-year-old elected presidency.

"Constitutional changes should never be undertaken lightly," he said, encouraging MPs to consider the proposals before them with an eye on the next 50 years and beyond. The goals of the constitutional review are to ensure that the institution of the elected presidency and the Constitution continue to be relevant, he said.

Drawing from his personal experience since being elected to the office in 2011, Dr Tan said an important dimension of his role has been working with the different ethnic groups that make up Singapore's multiracial society.

The president remains a symbol of Singapore's unity and, therefore, it is important that the office of the president upholds multiracialism, he said. This is a core value of Singapore that underpins its social cohesion and the harmony it enjoys.

While Singapore should aspire in the long run for minorities to be elected as president without the need for any intervention, "we also need to recognise the current realities", said Dr Tan.

He noted that all but one of the elected presidents, since the scheme started, have been Chinese.

These realities are why he thought the proposed change to reserve a presidential election for a specific ethnic group, if a member of that group has not been the president for five terms, was a balanced approach.

He also highlighted the president's role as a custodian of Singapore's national reserves and of the integrity of its public service.

As the president can disagree with the Government on these matters, he must be qualified to do so.

This is why Dr Tan agreed with the move to update the criteria individuals need to meet to be able to run for the office.

"From my own experience, the scope and complexity of the presidential oversight on Singapore's key assets have increased significantly, even in the span of five years of my term," he said.

"My finance background was useful in helping me understand the technicalities of the Government's proposals, but the decisions often also require good policy acumen and a sound judgment on what is right for Singapore," he added.

But while the president acts as a custodian, this does not necessarily mean that he acts in opposition to the Government.

There is a difference, said Dr Tan.

He cautioned that the elected president must act in accordance with the roles prescribed in the Constitution, and not hold back the elected government of the day from performing its executive role.

Dr Tan added: "We must rely upon the wisdom of our electorate to elect a president who is able to work with the Government of the day for the proper and effective governance of Singapore."

He said that as president, his working relationship with the Government has been harmonious.

"The Government keeps me informed of all its major decisions. On a regular basis, the Prime Minister and I meet over lunch and on other occasions, for him to brief me on his preoccupations and intentions, and to exchange views on the strategic direction in which Singapore is heading," said the President.

"Our relationship is built on mutual trust and respect. This, to me, is key to the effective functioning of our system."

Dr Tan also noted that the president had previously been described in the House as a goalkeeper.

"Indeed, if he fails to do the job well, no matter how good our strikers are, more goals will be scored against us and Team Singapore will be set back," he added.

"We need a capable goalkeeper who works with the other players. Only then will Team Singapore continue to do well in the global league, against competitors who may be bigger, stronger and more intimidating."