Rachel Reeves must spare pensioners from punishing tax rises in the Budget or Labour will “pay the price” at the ballot box. Fears are mounting that the Chancellor will clobber OAPs with a double-whammy by hiking income tax and extending the freeze on the lower tax threshold.

Campaigners have warned that the measures are more unpopular than when Ms Reeves snatched away the winter fuel allowance. More than 160,000 people have now signed a petition demanding a stop to the so-called “retirement tax” before the November 26 showpiece.

The stark warnings come as the Chancellor desperately looks for ways to plug an estimated £30billion black hole in the nation’s finances.

Dennis Reed, director of the Silver Voices campaign group, said: “Our members are spitting blood over the intended attack on their living standards in the coming Budget.

“We support taxing the very wealthy to improve public services but these tax hikes, likely to target pensioners, will hammer all older people on low and modest incomes.

“Our members ask, what have we done to deserve this vicious and vindictive treatment in our twilight years?”

Mr Reed said the political impact of introducing either policy would be hugely damaging for Labour.

“It looks like the anti-pensioner outfit the Resolution Foundation have been delegated the task of devising a Budget which will make pensioners pay for opposing the scrapping of the winter fuel payment,” he said.

“Just like that campaign, if Labour pushes these plans through, they will pay a big electoral price”.

The petition – Stop the state pension being taxed: Raise tax threshold. Support Colette! – can be found on the change.org website.

It has been set up to help people like 75-year-old widow Colette Rogers.

She is entitled to a proportion of her late husband’s state pension as well as her own, and found for the first time this year that the combined total took her over the tax threshold by about £1,000, which is now being taxed.

Her small NHS pension of £37 a month, earned as a GP practice nurse, is also being taxed. This comes after she lost her winter fuel payment last winter.

Ms Rogers said: “Faced with a 2p rise in tax and personal allowances remaining frozen, my standard of living will fall dramatically and it will reduce my quality of life too, as I have disabilities.

“How will I manage? Others in my position, too?”

Ms Reeves has all but confirmed she will break Labour’s flagship manifesto commitments on tax in a fortnight’s time.

She told BBC Radio 5 Live on Monday: “It would, of course be possible to stick with the manifesto commitments, but that would require things like deep cuts in capital spending and the reason why our productivity and our growth has been so poor these last few years is because governments have always taken the easy option to cut investment – in rail and road projects, in energy projects, in digital infrastructure.

“And as a result, we’ve never managed to get our productivity back to where it was before the financial crisis.

“So we’ve always got choices to make, and what I promised during the election campaign was to bring stability back to our economy, and what I can promise now is I will always do what I think is right for our country.”

She added: “I will do what I believe is right for our country, and sometimes that means not always making the easy decisions, but the decisions that I think are in our national interest.”

Shadow Chancellor Sir Mel Stride said: “Rachel Reeves said she would not be coming back with more tax rises. Now she is planning to go back on her word yet again.

“If these reports are true, it would be another hammer blow for pensioners.

“Reeves can point the finger all she likes, but this Budget black hole is of her own making – and now pensioners look set to pay the price for her failure to get a grip on spending.

“A future Conservative government would focus on controlling spending, not squeezing those who have done the right thing and worked hard all their lives.”

The Resolution Foundation, a Left-wing think tank closely embedded within the Labour movement, is pushing for a policy that would raise income tax by 2p while cutting National Insurance by the same amount.

This would shift the burden onto those who do not pay National Insurance – including pensioners, the self-employed and landlords – while leaving most workers’ pay packets unaffected.

Publishing its pre-Budget report last week, the think-tank, whose former chief executive Torsten Bell is now a minister at the Treasury, insisted: “Pensioners’ living standards have increased by much more than those of working age.

“Typical pensioner incomes have increased by 21% over the past 20 years compared with just 4% for those of working age – and with the state pension going up £560 next April, only pensioners with incomes above £40,000 would be worse off overall in cash terms.”

Freezing the lower tax threshold would also drag many more pensioners into paying tax.

According to government data, almost 7.8million state-aged pensioners pay the basic tax rate of 20%.

A Treasury spokesperson said: “We are committed to helping our pensioners live their lives with dignity and respect. Thanks to our commitment to the Triple Lock, millions will see their pension rise by up to £1,900 this parliament.”