John McDonnell has attacked George Osborne’s economic credibility ahead of today’s Budget speech – and accused the Chancellor of “taking us back to the old politics of spin”.

Shadow Chancellor McDonnell said this morning that the “Budget looks more like a press stunt to hide George Osborne’s failures than about any serious policy.”

He also claimed Tory austerity is causing mounting uncertainty over funding for the “infrastructure projects that the Chancellor is set to reannounce”, pointing out that only one in five projects in his pipeline of key road and rail projects is under construction.

He added that Osborne’s policies will likely hit the vulnerable hardest, saying:

“When you put all this together with the possible tax cuts that are floated, which will be paid for by more stealth taxes and cruel cuts to the disabled, this Budget from George Osborne looks to not be about the future, but taking us back to the old politics of spin and little substance.”

While Jeremy Corbyn, as Leader of the Opposition, will lead Labour’s response to the Budget in the House of Commons today, it is John McDonnell who is taking a much more high profile media presence today.

In an article for today’s Independent, McDonnell wrote that there is “no economic justification” for Osborne’s “severe austerity”.

“There is not a single credible economist to be found who will support his ludicrous target to generate a £10bn surplus by 2020,” he writes.

“Osborne’s plans are entirely irresponsible. These is no economic justification for the Chancellor’s cuts.”

And McDonnell laid the blame with Osborne for a series of unhealthy economic stories. He wrote:

“Business investment has slumped again recently. Zero-hours contracts are at a record high. Wages remain below their 2008 levels. Manufacturing has still not recovered from the crash. Our current account deficit with the rest of the world has reached record highs.

“Productivity growth, the essential ingredient in delivering rising living standards, has stagnated. The gap between the UK’s productivity and those of the Germany, the US and France is the widest it has been for a generation.”