Last night, Tory leadership contender Kemi Badenoch said the public were ‘seeing the grim economic reality of a Labour Government’, adding: ‘Their union-backed student politics will give us higher taxes and lower growth.

‘The Conservative Party needs to win back the trust of voters and kick out this Government as soon as possible.’

Briefings from the Treasury indicate Ms Reeves is planning to freeze income tax thresholds and raise taxes including inheritance tax, stamp duty, fuel duty, capital gains tax, employers’ National Insurance contributions and air passenger duty, known as the ‘holiday tax’.

There are also likely to be ‘sin taxes’ on vaping and gambling companies.

If the briefings are accurate, it would be the biggest tax-raising budget in history – vindicating Tory claims during the election campaign that Sir Keir would drop a ‘tax bombshell’ on the electorate if he was given a large majority.

The poll by Opinium puts the Tories ahead of Labour by 23 per cent to 21 per cent when voters were asked which party was most likely to improve their financial situation.

The last time the company had the Tories ahead on the measure was in February 2021, when Mr Johnson was still in Downing Street, when the Conservatives had a five-point lead.

Labour MPs are growing increasingly concerned about the impact of the planned Budget measures on their voters, and in particular the growing perception that the party has breached its manifesto promise not to increase National Insurance nor income tax rates.

As Rishi Sunak’s July election defeat loomed, Sir Keir Starmer’s party led the Conservatives by 15 per cent on the issue

The freeze on income tax thresholds for two years beyond the promised end in 2028 is expected to bring in an extra £7 billion by pulling 1 million more people into higher rates of tax.

Labour sources have insisted this does not breach the manifesto promise that the ‘rates’ of income tax would not rise from the current levels of 20p, 40p and 45p.

The party also vowed not to raise VAT or National Insurance on ‘working people’. Labour now claims the pledge did not cover imposing National Insurance on employer pension contributions.

Sir Keir has faced a strong Cabinet backlash over planned spending cuts of up to 20 per cent.

Among those who have written to the PM expressing alarm are his deputy Angela Rayner, who is also Housing Secretary, Justice Secretary Shabana Mahmood and Transport Secretary Louise Haigh.

Ms Reeves is understood to have also clashed with Environment Secretary Ed Miliband over the cost of his beloved green projects.

It is understood that one Cabinet Minister is still refusing to agree to the cuts.

With Ms Reeves warning of ‘difficult decisions’ ahead, The Opinium poll reveals how pre-Budget briefings have created a mood of deep economic pessimism: 49 per cent of those surveyed believe that the UK economy will get worse in the next 12 months, compared with 34 per cent in May.

There are likely to be ‘sin taxes’ on vaping and gambling companies (stock image)

Almost a half, 46 per cent, described their financial situation as ‘coping’, while over a fifth consider themselves as ‘struggling’.

Voters believes that most taxes are too high – council tax, fuel duty, inheritance tax, the basic rate of income tax and capital gains tax. They think the top rate of tax and corporation taxes are too low.

The poll found Labour and the Tories are level-pegging when it comes to which party voters think would be best at setting tax levels, while Labour remains ahead on improving public services.

The Budget measures, combined with the freebie scandals which have dogged Sir Keir Starmer, have pushed the Prime Minister’s approval rating down to a record low of minus 31 per cent.

Separate polling by the Portland consultancy has found that just 18 per cent of voters have swallowed Labour’s efforts to blame the planned measures on their economic inheritance from the Tories.

Even among Labour’s own voters, only 27 per cent agree with the sentiment: ‘The previous Conservative government wasn’t honest about the state of public finances’.

Among those who have written to the PM expressing alarm at planned spending cuts is his deputy Angela Rayner (right)

Ms Reeves told Ministers at Tuesday’s Cabinet meeting that plans to fill a £22 billion hole in the public finances will be enough only to ‘keep public services standing still’, and she needed an additional £18 billion to fund a cash injection for the NHS and avoid real-terms cuts to key departments.

Allies of Ms Reeves have said the Budget would reveal her ‘vision’ – not the Prime Minister’s. One ally said: ‘Make no mistake, this will be Rachel’s Budget. You’ll see very little of Keir in it. It will be her vision for Britain’s future.’

James Crouch at Opinium said: ‘Labour’s honeymoon ended a long time ago, but the chances of the Budget turning things around look slim unless there’s a mighty rabbit to pull out of the hat.

‘With public pessimistic about the direction of the economy, and approval ratings for the PM and Chancellor at a new low, the government should expect a turbulent couple of weeks.’

Opinium Research carried out an online survey of 2,050 UK adults from October 16 to 18. Results are weighted to be politically and nationally representative.