Nadhim Zahawi has denied the government has "gone missing" as Boris Johnson was pictured enjoying his second foreign holiday of the summer.
Speaking to broadcasters, the chancellor was asked whether the prime minister is absent "at a time of national emergency".
Mr Zahawi replied: "I don't agree with that, nor do I recognise that."
The chancellor said his department's officials are "literally working night and day" to make sure options for easing the burden of rising living costs "are on the table for the incoming prime minister".
He added: "If I don't get that £400 out the door in the next couple of months to reduce those energy bills - in Great Britain, but also the equivalent in Northern Ireland - then I would have failed those people.
"If I don't make sure that if you are a pensioner, [you] get the additional £300 in the next few months, I would have failed.
"If I don't make sure you get the £150 if you are disabled, I would have failed.
"So we are working night and day to make sure we get this done and have all the options for the incoming prime minister for more help for both households that are really struggling and for small businesses."
On Monday, Downing Street confirmed Boris Johnson is not expected to take part in any engagements this week as he enjoys his second foreign summer holiday in less than a month.
Over the weekend, Mr Johnson was spotted in Greece as UK households grapple with the deepening impact of the cost of living crisis.
The prime minister took a holiday earlier this month despite warnings of further inflation and the threat of a recession later this year.
The PM's official spokesperson told reporters that the PM "is on leave this week" and that he is not doing day to day work.
Deputy Prime Minister Dominic Raab is able to deputise for him in any meetings, the spokesperson said, but none are currently scheduled.
The spokesperson added that Mr Johnson "will be contactable" and "kept informed of any urgent issues".
The PM's official spokesperson also confirmed that Mr Johnson is paying for his trip but declined to say whether his security is funded by the taxpayer.
Probed on why Mr Johnson could not wait until his successor is appointed on 5 September before going abroad, the PM's spokesperson said he could not get into the details of that but said, "government activity continues".
"I can't get into the decision around timings but he is on leave this week. He will be back this weekend," he told reporters.
"Over recent weeks we've made a number of significant announcements and will continue to do so in the coming days."
Removal vans were spotted outside Number 10 earlier this week.
The Times newspaper has reported that Mr Johnson is spending a week-long holiday in the country, with locals spotting him shopping alongside wife Carrie Johnson in a supermarket in Nea Makri, a town to the east of Athens.
Labour has criticised the PM, accusing him of treating recent months as "one big party".
A party spokesperson said: "On the evidence of the last few months it seems to make little difference if the prime minister is in the office or on holiday as he has continually failed to meet the challenge of the Tory cost of living crisis.
"It's all just one big party for Boris Johnson while the country struggles to pay their bills."
Analysts have predicted that typical energy bills could rise to approximately £3,500 in October and more than £4,200 in January.
Bills are set to cost more than two months of average wages next year unless the government intervenes, a report has suggested.