A poll conducted by Age UK revealed that 75% think the government should maintain the mechanism which means pensions rise by the highest of 2.5%, inflation or average earnings.
The triple lock — a Tory manifesto pledge — was suspended last year but was set to be reinstated from April next year.
However, prime minister Sunak has refused to commit to it.
The polling also found high levels of support for benefits such as pension credit to be increased in line with inflation.
Without this, Age UK warns that millions of the poorest pensioners, children and families will be plunged below the bread line.
Caroline Abrahams, charity director at Age UK, said: “We are hearing some deeply concerning stories from older people about the drastic measures they are taking to save money — for example, preparing coffee with hot water from the tap so they don’t have to boil a kettle, and regularly eating a handful of biscuits rather than preparing a proper meal.
“Our biggest worry is that as the weeks go by and prices for everyday items continue to rise, growing numbers of older people will resort to strategies like these, putting their health and wellbeing at risk.”
The charity has warned that without clarity of what will happen with the triple lock in April, many will not know if they can afford to turn on the heater during winter.
“Without the knowledge that this important safety net will kick in from April, many older people simply won’t have the confidence to keep their homes warm this winter — and Age UK fears that the threat of an unaffordable bill in the spring could mean that hundreds of thousands won't even try, seriously jeopardising their physical and mental health,” Age UK said.
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The poll also found that 35% of over-60s said they would be less likely to vote Conservative in a general election if the government breaks its manifesto commitment to increase the state pension by the triple lock.
A pensioner couple said: “We are rapidly running out of cash, due to increased cost. We have stopped using our electric kettle and use a kettle on the gas stove and will have to only heat one room when winter starts.”
A woman who cares for her husband in his late 80s said that the choice is between heating or food.
“We cannot afford the rise in energy and food bills. Having gone through last winter where we could not afford to heat our home - a small two bedroom apartment — all electric — heat or eat was the choice. We are terrified about the price rises that are forecast.
“My husband is 88 years old and has blood and bone cancer, and I’m his full-time carer. We worked all our lives, paid what was required, and now find ourselves threatened by energy suppliers, who do not care at all about the survival of the vulnerable.”
Raising state pensions and benefits in line with a record high inflation would cost £11bn next year.
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Chancellor Jeremy Hunt is trying to plug a 60bn "black hole" in government finances and has warned of a “tough road ahead” as a raft of spending cuts and tax rises to help the government balance the books are widely expected.
Abrahams said: “‘To govern is to choose’, they say, so we fervently hope that at the Autumn Statement the chancellor chooses to do the right thing and acts to protect older people on low incomes.
The Autumn budget will be presented on 17 November.