The draw on the reserves announced in the Budget Statement was a continual topic throughout the three-day debate, but Thurday's session threw up the most pointed questions.

According to the Constitution, the nation's reserves can only be used if two parties give consent - one is the Government of the day, the other is the Elected President. Hence, there are 'two keys' to the reserves.

The Government is asking for approval to use $4.9 billion from the reserves to fund one-off measures to boost the economy, including the $4.5 billion Jobs Credit Scheme.

And it said that the President has already given in-principle approval for this.

Opposition MP Low Thia Khiang (Hougang) asked if the system was such that the two keys operated in tandem.

'When the Government key says unlock, the other key unlocks automatically. And I wonder whether the second key has always been there on the safe,' he said.

Ms Irene Ng (Tampines GRC), in turn, asked if the President had given the nod without being told exactly how much was to be taken out.

Mr Inderjit Singh (Ang Mo Kio GRC), wanted to know what deliberation the President went through.

'If we could get a sense of what they discussed and what process they went through, then that may clear many of these questions,' he said.

The questions came after Finance Minister Tharman Shanmugaratnam spelt out at length the government's consultation with the President.

During his speech and in his replies later, he stressed the second key did not turn automatically.

"This is not a wayang," he said. "This is about a government that in the exigencies of the circumstances had to craft, within a short period of time."

He also reminded the House that the earlier-than-normal Budget announcement this year meant a tighter time frame.