Sir Keir Starmer faced fury after claiming pensioners will be “better off” under Labour.
The Prime Minister insisted protecting older people was a priority for him despite axing the winter fuel payments for 10 million people.
He said the triple lock on state pensions, which will be paid out next spring, means some senior citizens will receive an extra £400.
But Silver Voices said the comments were an “insult” to pensioners and “defied belief”.
Director Dennis Reed added: “The triple lock is supposed to compensate for all household increases, not just energy, and we still see food and essentials prices soaring.
“The very large majority of older people are still on the old state pension (for those retiring before April 2016), the maximum rate of which is £169.50 per week.
“This will rise next April by £7 per week to £176.45.
“Well off politicians wouldn’t blink at spending that on a meal out, or a Taylor Swift concert.”
An Express crusade to save the payment has been backed by MPs from across the political spectrum.
A petition calling for the government to protect pensioners in the budget will be handed in to No 10 today (MON).
Mr Reed added: “I am delivering a mass petition to 10 Downing Street tomorrow, with the Express, calling for the Budget to protect older people, signed by about 150,000 so far.
“I will be happy to engage in discussion with Sir Keir on his doorstep, to put him right on the facts, if he is around.”
Chancellor Rachel Reeves has faced accusations she is carrying out an “attack on pensioners” by axing the winter fuel lifeline worth up to £300.
Several lifetime Labour voters have told how they will never vote for the party again after its “cruel” move.
The government is axing the universal winter fuel allowance, which is £200 for pensioners under 80 and £300 for those over to save £1.5 billion.
Only those claiming pension credit and some other benefits will be eligible.
Ms Reeves announced the decision just three weeks after taking office to fill a £22 billion blackhole in spending.
But critics point out half of that money is for big public sector pay hikes that were signed off without securing any changes in working practices in return.
Analysis carried out by the Labour Party in opposition found that restricting winter fuel payments could cause 3,850 deaths.
Almost all pensioners on the breadline will lose their winter fuel allowance, according to research by Age UK.
The charity has warned around eight in ten older people with incomes just below or above the poverty threshold will be stripped of the payments this year.
It fears there will be a looming “disaster” when the weather turns unless there is a u-turn in the Budget.
Nearly 23% of those who will lose the allowance live in poverty or just above the poverty line, with 800,000 of those over 80.
Around 1.1 million pensioners with a disability and nearly as many older people who live alone who struggle to make ends meet will be affected.
The decision has also caused division on the Labour benches, with the party’s MPs and peers raising concerns about the impact it will have.
Around 50 of its MPs stayed away from a vote on introducing the changes in the biggest rebellion so far for the new government.
When asked by the Express whether he could reassure retirees that they had already taken their hit and will not be worse off after the budget, Sir Keir said: “l’m very concerned to make sure pensioners are better off and that’s why we’re stabilising the economy.
“What that does is allow us to keep to the triple lock. By keeping the triple lock that means that the pension will go up by over £400 next year.
“That’s in addition to the money that it went up this year, which was £900 for the state pension.
“That’s the position on pensions but I am very concerned to make sure they’re both protected and better off under a Labour government.”
