Tory ministers have privately expressed fear that government inaction on the emerging cost of living crisis could leave the country facing “a nightmare” by Christmas.

Boris Johnson was accused by one frontbencher of trying to resolve struggling supply chains by “being optimistic and leaving it up to businesses to pick up the slack”, while a second called the response so far “suboptimal”.

Another said: “It could all build up to be an absolute nightmare for both the public and us, especially if – in the next few months – the economy goes into negative growth that we could have done more to prevent.”

Just days after a party conference speech, which was criticised for neglecting to mention the gas price crisis that has forced firms to go bust, shortages of food in some shops and a lack of hauliers and pork farmers, Johnson appointed a new adviser – former Tesco chief executive David Lewis – in an attempt to resolve blockages in supply chains.

A government source said they were trying to avoid ending up in a spiral where several problems compounded, saying: “Right now, we don’t expect the shelves to be empty – but there might only be one brand of cranberry sauce on the shelf rather than five.” But they added: “We’re just worried about the practicalities of getting past 25 December.”

It emerged on Friday that one in six adults in Britain said they had been unable to buy essential food items in the past fortnight. The startling figure was released by the Office for National Statistics, which also found 13% of adults reported having to wait longer for prescriptions.

The Guardian also understands that the deal worth up to tens of millions of pounds to restart production at a CF Fertilisers plant in Teesside which produces carbon dioxide as a byproduct is not likely to be extended. The gas is a crucial component of making dry ice to keep food fresh, as well as in the stunning of animals before slaughter.

Ministers have been buoyed up by the restarting of manufacturing at another factory in the region, run by Ensus, which provides 40% of the country’s CO2 supplies, leading sources to signal no more taxpayer funds would be needed to prop up CF Fertilisers.

Alongside concerns about food and petrol, investment firm Scottish Friendly found households were expected to absorb an average of at least £441 worth of energy and petrol price rises this winter.

Keir Starmer accused Johnson of “turning on the poorest” after the universal credit uplift ending earlier this week, saying it came “at the worst possible time because prices are going up”.

The Labour leader said: “Whether that’s fuel or food, or energy prices, and this is going to drive families and children into poverty and for the government to turn on the poorest as we come out of the pandemic is just so wrong.”

Starmer said a Labour government would not have made the cut but that the whole welfare system would be overhauled because, he said, it “traps people in poverty”.

A 1.25 percentage point national insurance hike next year is also expected to add at least another £254 to the tax bill of a median wage earner.

Tory MPs also voiced fears about the energy price cap “undoubtedly going up quite considerably” next spring, which could “affect people big time”. Dr Neil Hudson, a Conservative backbencher and former vet, said it was distressing to hear farmers being forced to slaughter healthy pigs, and added the government should “act now to stop this animal welfare crisis”.

While the Department for Environment, Food and Rural Affairs is lobbying for the requirement for the level of English language needed to be spoken by agricultural workers to be lowered, the Home Office is said to be “digging their heels in”.