The prime minister has been accused of leading a “zombie” government and failing to provide reassurance to families anxious about soaring energy bills expected to hit almost £3,600 this October.
Labour accused Johnson of treating his final weeks in office as “one big party” after he was filmed shopping for groceries in a supermarket in Greece.
Greek news websites reported that Johnson and his wife Carrie were in Nea Makri, a coastal town near Athens, and only a few hours away from where his father Stanley has a villa.
The prime minister returned from a holiday in Slovenia only last week, having enjoyed a break at a mountain resort which offered “healing energies”.
A Labour 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.”
The Labour official added: “It’s all just one big party for Boris Johnson while the country struggles with the Tory cost of living crisis.”
Liberal Democrat MP Munira Wilson said the PM and his “zombie government” had shown “a complete failure of leadership” in recent weeks.
“As the country is gripped with drought, our health service collapses, and the cost of living emergency turns into a cost of living catastrophe, Boris Johnson puts his out of office on for the second time in two weeks.”
Speaking on Thursday, Johnson said he could not offer any new help on energy bills now – but the public can expect the next PM to provide extra financial support in September to tackle spiralling living costs.
The latest Opinium survey shows Truss has a healthy lead over Sunak in the Tory leadership race, ahead 61 per cent to 39 per cent among Tory members.
But the poll shows signs of regret at the PM’s political demise over the Partygate scandal, and an apparent lack of enthusiasm for either of his would-be successors.
In a head-to-head contest between Johnson and Truss, 63 per cent of Tory members would opt for the caretaker PM, compared with 22 per cent support for the foreign secretary.
Results were even starker in a Johnson versus Sunak contest. Some 68 per cent of Tory members prefer the PM over the ex-chancellor.
Labour leader Sir Keir Starmer has also been accused of going “missing” during the cost of living crisis as he took a summer break.
Starmer, who insisted this week that his party has been “leading” on the cost of living, is setting out his party’s plans to freeze October’s energy price cap rise as part of a “comprehensive” cost of living plan on Monday.
Lib Dem leader Ed Davey – who proposed a price cap freeze a week ago – tweeted Labour: “Glad you liked my proposal to cancel the energy price rise. I also have some thoughts on electoral reform that you’re welcome to adopt.”