He has told Cabinet colleagues to expect "incredibly difficult decisions" as he gets to grips with the biggest financial crisis facing the country for decades.
But the Prime Minister insisted he could deliver a future "full of opportunity" once the economy recovers.
Nothing is off the table as Mr Sunak and Chancellor Jeremy Hunt continue work on November's make-or-break financial statement, which is set to include huge tax hikes and spending cuts amounting to £50billion.
Downing Street has refused to rule out controversial measures, including realterms cuts to state pensions, new taxes on workplace pension contributions or reversing planned defence spending increases.
Insiders say that Mr Sunak was appalled by the mess he inherited after becoming PM less than a week ago, while senior Tories fear that the party's civil war could reignite over a series of "flashpoint" issues such as immigration.
Cabinet colleague Nadhim Zahawi last night urged voters to have faith in the Prime Minister, saying: "While we face difficult months ahead, we have in Rishi Sunak the leader the country needs to steer us through" It comes as:
Tory MPs admitted they had "stared into the abyss" and narrowly avoided electoral oblivion;
There was anger at "malcontents" refusing to unite behind the new PM; Labour seized on Treasury figures suggesting former Prime Minister Liz Truss cost the nation £73billion; A poll showed voters are less likely to back the Tories now Mr Sunak is PM.
Conservative MPs rallied behind Mr Sunak last night but warned the new spirit of unity could easily be shattered as the Government makes decisions on a series of divisive issues.
One said: "There is a degree of unanimity because we have stared into the abyss. We need to make sure that we at least give the impression of uniting.
Denne historien er fra October 30, 2022-utgaven av Sunday Express.
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Denne historien er fra October 30, 2022-utgaven av Sunday Express.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
Allerede abonnent? Logg på