The Office for Budget Responsibility (OBR) said departments other than the NHS, schools and defence would be hit by “real-terms cuts to their budget” – putting the figure at £15bn a year.
At the Treasury committee, Mr Sunak was warned he should be suffering “sleepless nights” and was told: “The current numbers you have got in there on spending are unrealistic.”
But the Chancellor insisted his critics are wrong, telling MPs: “No, spending grows over the parliament and grows in every year.
“I think what you’re referring to are changes in forecasts from previous fiscal events – that’s not a cut in spending,” he claimed.
Later, Mr Sunak argued his spending plans contained the “same real terms growth rate of 2.1 per cent” as previously – and, confusingly, said the total “flexes with the different GDP deflator”.
The comments came as Mr Sunak:
* Was upbeat about the post-Covid economic recovery, saying: “It seems consumption can and will bounce back reasonably quickly when things are reopened.”
* Said the controversial 1 per cent pay rise for nurses was “all one government policy” – when asked if he had been involved in the recommendation.
* Refused to say if he has personally benefited from the Moderna share price rise after its vaccine success – insisting his financial interests, in a blind trust, are “transparent”.
* Said he “would not want to be breaking the law” by making huge overseas aid cuts without a promised vote by MPs – but refused to say it will go ahead.
* Would not accept the UK had “a housing crisis” – preferring to say it was “a challenge for young people to find their own home”.
In its post-Budget report last week, the OBR warned of the “legacy that the pandemic could leave behind for public services” – with nothing set aside for “Covid-related costs”, from April.
“The Chancellor’s response so far has been to cut around £15bn a year from total departmental spending in the years beyond 2021, including a further £4bn cut in this Budget,” it said.
Mel Stride, the Tory chair of the Treasury committee, said: “Is it just not the case that the current numbers you have got in there on spending are unrealistic and are just going to come under unbearable pressure?”
Mr Sunak admitted he would have to “prioritise within a pie”, but insisted: “The pie is growing at a rapid rate over the course of this Parliament – and, relative to the size of our economy, is a large pie.”
On the Moderna shares bump, he said: “All my disclosures are in accordance with the Cabinet Office guidelines and have been gone over rigorously, and are published in the normal way.”
But Labour’s Angela Eagle replied: “You are not prepared to add that extra bit of information for us today whether you have benefited personally? I think that is about as opaque as it comes.”
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