A Labour government will pave the way for “a parliament of tax rises and spending cuts”, according to a top think-tank.
The left-of-centre Resolution Foundation issued the warning after Keir Starmer published his party’s election manifesto.
Starmer said Labour would end the “chaos” of the last 14 years of Tory rule and boost economic growth to fund his spending plans.
But critics said the 133-page blueprint contained little detail on how the party would achieve its aims in power.
Mike Brewer, the Resolution Foundation’s interim chief executive, said: “Labour have taken a politically cautious approach to tax and spend, with modest proposals on either side of the ledger.
“This approach sets the scene for a parliament of tax rises and spending cuts for unprotected departments. Even then, a modest dose of bad economic news could force a fresh round of tough fiscal choices if the debt rule is to be met.
“The manifesto includes stretching ambitions for employment and GDP. These reflect the scale of change needed if we are to transform growth and living standards.
“But with much of Labour’s economic strategy resting on contentious reforms, rather than a step-change in investment, it’s unclear whether the measures set out will be enough to end stagnation – let alone secure the strongest growth in the G7.”
The contained pre-announced pledges including plans to put VAT on private school fees, extend the windfall tax on oil and gas companies, and reform planning rules to build 1.5 million more homes.
Other policies include lowering the voting age to 16, recruiting 6,500 more teachers, delivering 40,000 more NHS appointments to bring down waiting lists and setting up a Border Security Command to tackle the small boats crisis.
In all, Labour set out £8.5bn worth of tax rises - but insisted they would not hike income tax, VAT or National Insurance.
However, Paul Johnson of the highly-respected Institute for Fiscal Studies criticised the lack of detail contained in the manifesto.
He said: ”It sets out lots of the problems we’re facing across areas of public services and promises to make things better. What it doesn’t do is tell us how, and certainly doesn’t allocate any spending, to achieving that.”