Shadow chancellor Rachel Reeves has promised that there will be “no additional tax rises needed” beyond those she has set out if Labour wins the general election.
In her first major speech of the election campaign, Ms Reeves said that every Labour policy “will be fully funded and fully costed – no ifs, no ands, no buts”.
That includes recruiting thousands of additional teachers and introducing 40,000 NHS appointments every week.
However, Prime Minister Rishi Sunak claimed that Labour’s plans will cost “every working family” £2,000 each.
He said that analysis was based on Treasury officials “crunching the numbers”.
Speaking at the engineering giant Rolls-Royce in Derby, Ms Reeves said that the Labour party “is being recognised as the natural partner of business, the party of growth and the party of enterprise”.
She said: “A few years ago, you might not have expected to have heard these things from the Labour party, think how far we have come in four short years.
On Tuesday, 121 former and current business leaders signed a letter endorsing the Labour’s economic plans ahead of the general election, saying it is “time for a change”.
In a letter published in The Times newspaper on Tuesday, 121 founders, chief executives, and former leaders at a range of financial services, retail and manufacturing firms said Labour has changed and “wants to work with business” on long-term growth.
They said: “For too long, our economy has been beset by instability, stagnation and a lack of long-term focus.”
Labour is borrowing from the Conservatives’ playbook in getting business leaders to endorse their economic plans.
Ahead of the 2015 election, 100 corporate leaders endorsed the Conservatives.
One of those, Malcolm Walker – the founder of supermarket chain Iceland – will now endorse Labour instead.
Other former Tory business letter signatories have told BBC News they will keep their counsel amid disappointment over Liz Truss’s mini-budget, the Brexit deal and a general expectation of a change of government.
Among those who have signed the letter in the Times is the TV chef and restaurateur Tom Kerridge, some chief executives of smaller companies, former Heathrow Airport chief executive John Holland-Kaye, JD Sports chairman Andrew Higginson and Wikipedia founder Jimmy Wales.
They also include David Cleevely, former chair of Raspberry Pi, the technology firm which has just announced plans to float the business on the London Stock Exchange and Karen Blackett, UK president of the advertising giant WPP.
But speaking to the BBC’s Today programme on Tuesday, work and pensions secretary Mel Stride pointed out that no chief executives of the UK’s very largest FTSE 100 companies were among the signatories.
Following the UK’s exit from the European Union (EU), many household names learned that taking sides in a key election period may annoy their customers.
It is also unclear how representative this group of Labour backers are of business in general and their sectors in particular.
Ms Reeves believes this public display of support for Labour will demonstrate its credibility to the public.
Some Conservative business figures said there had been no effort similar to 2015 to organise a Tory business endorsement letter.
Chancellor Jeremy Hunt’s advisers are known to be warning businesses about what they say is a move to French-style workers’ rights should Labour win.
Some top retailers have expressed concern about the plan, including a repeal of Conservative anti-strike laws.
But Mr Wales of Wikipedia told the BBC’s Today programme: “We’re not talking about an extreme left wing government by any means, we’re talking about a sensible, solid centrist government.”
He added that he is “very convinced” by Labour.
Chief Secretary to the Treasury Laura Trott said: “Rishi Sunak and the Conservatives have a clear plan that businesses can rely on.
“We took the bold action to deliver the biggest business tax cut in modern history”.
The Lib Dems told BBC News that businesses are “crying out for stability and certainty after years of the Conservatives’ chaos and mismanagement”.
“The Liberal Democrats would launch an industrial strategy to boost investment and reform the broken business rates system to support our high streets,” a spokesperson said.
The Green Party of England and Wales said it “would invest in the technologies we need to ensure a sustainable and secure future”.
“We need to ensure our economy works in a way that safeguards our climate and enables nature to flourish,” co-leader Adrian Ramsay said.
The Scottish National Party’s Drew Hendry accused Labour of “ignoring the most fundamental reason for the economic decline of the United Kingdom – Britain is broken and Brexit broke it”, adding: “Only the SNP will fight for a future back at the heart of the European Union.”
Plaid Cymru Treasury spokesman Ben Lake said his party would “invest in the Welsh economy to drive growth and reduce inequality”.