A custodial president who is democratically elected remains the "most workable and effective solution for Singapore for the present", the Government said yesterday.
It rejected the Constitutional Commission's suggestion of reverting to an appointed head of state who would focus on the historic role of being a unifying figure for the nation.
As for the custodial role of safeguarding the reserves and the integrity of the public service, the panel said in its report made public last week that this could be assumed by a group of appointed experts.
But the Government said retaining the elected presidency better serves the tenets of democracy.
"Whether the Government makes decisions with the president's concurrence, the president vetoes the Government's decision, or Parliament overrides the president's veto, it is always an elected institution that represents Singaporeans in making important decisions relating to our financial reserves and the integrity of the public service," it said.
It offered four reasons the presidency should remain an elected institution.
First, the president's custodial powers - the "second key" - should be held by someone with direct mandate from Singaporeans. This ensures that he has the moral authority to veto an elected government, it said.
It pointed out that the panel had acknowledged that for a president to have custodial powers, he must have the democratic mandate.
Yet appointing a group of experts to serve this role would lead to the same lack of independence and mandate that led the commission to reject an appointed custodial president, it said.
Second, the proposal of an appointed body of experts could lead to inefficiency and a lack of rigour while executing its custodial powers.
That is because the experts can only force a debate on its objections but not actually veto any initiatives - presumably because they lack the democratic mandate to do so, the Government said.
Third, despite the potential tension between the president's historical and custodial roles, all three elected presidents "have been able to perform these two roles with distinction".
The White Paper said such success depends on the character and qualities of the person elected: "All presidential candidates must aspire towards playing both roles well."
Fourth, the tension between the president's two roles can be mitigated, even if not entirely eliminated.
This could be partially achieved by implementing rules to govern election campaigns and reduce the risk of presidential elections becoming politicised, since the president has no role in initiating policies.
To that end, the Government said it would study the panel's proposals to restrict or exclude acts that might cause divisiveness, and impose sanctions on candidates who take positions that are incompatible with the office of president.
Its decision on the necessary changes will be made known in due course, the White Paper said.