George Osborne is facing renewed pressure to abandon a planned increase in fuel duty, amid warnings the rising price of petrol was putting household budgets under more strain.
As MPs prepare to vote on Monday on the planned 3p a litre increase due in January, the consumer organisation Which? said more people than ever before were being forced to cut back on motoring costs.
It said its latest polling found a record 85% of people expressed fears about rising fuel prices - a nine point increase since July.
Those saying they would cut back on motoring costs rose seven points to 39% - another record high - while one in 10 said they had had to dig into their savings to cover their motoring costs.
Overall, one in three people said they were finding it difficult to live on their current income, with 33% also cutting back spending on the essentials last month. Getting on for half - 44% - said they were planning to cut back on food and groceries in the coming months.
Which? said the figures showed 8.7 million households curbed their spending on essentials last month, while 6.4 million households dipped into their savings to cover their outgoings.
Which? executive director Richard Lloyd said: "Rising fuel prices are the number one consumer worry and people are already telling us they're having to cut back and dip into savings just to get by.
"On the back of inflation-busting energy bill rises and increasing food prices, consumers can little afford another hit on their household budget. We're calling on the Government to think again about their plans to increase fuel duty in January.
"The forthcoming Autumn Statement must focus on measures that will help put money back in the pockets of consumers, because the economic recovery is at risk if we don't increase consumer confidence."
For Labour, shadow treasury minister Cathy Jamieson said: "Families, pensioners and businesses are still feeling the squeeze. Labour will vote on Monday for a delay in this fuel duty increase at least until next April."
A Treasury spokesman said: "The Government recognises that the rising price of petrol is a significant part of households' day-to-day spending.
"Since coming to office the Government has listened to the concerns of motorists about high pump prices and acted. Fuel is now 10p a litre lower than under the previous government's plans."
:: Pollsters Populus interviewed 2,100 UK adults on behalf of Which? online between October 26 and 28.