Rachel Reeves races to save her job after 'misleading public about fake £30bn black hole'

Elsewhere, she said the Office for Budget Responsibility would downgrade its assessment of Britain's productivity.

But on Friday, the OBR revealed it had actually told the Treasury on September 17 the "black hole" was £2.5billion - less than a tenth of what she claimed.

OBR chief Richard Hughes had written to the Treasury Committee confirming that "at no point" did the Chancellor face a black hole greater than £2.5billion.

By October 31, the watchdog said the black hole had disappeared, and had in fact been replaced by a £4.2billion surplus.

Just four days later, she gave her pre-Budget Downing Street address warning how poor productivity would have "consequences for the public finances" - while families would need to "do their bit" to plug the gap.

She added: "I'm being honest with people."

Now, Ms Reeves is facing cross-party condemnation - while the Treasury is scrambling to defend her.

Reform UK's deputy leader Richard Tice said the Chancellor had "deliberately scared businesses, consumers and the markets" before her Budget.

"She has deliberately crashed the economy and must now consider her position," he said.

Tory chief Kemi Badenoch outright accused her of "lying to the public" as she branded Ms Reeves "shameful".

"Yet more evidence, as if we needed it, that the Chancellor must be sacked," Ms Badenoch blasted.

"For months, Ms Reeves has lied to the public to justify record tax hikes to pay for more welfare.

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"Her Budget wasn’t about stability. It was about politics: bribing Labour MPs to save her own skin. Shameful."

There are also questions over a stretch of time between Ms Reeves's pre-Budget briefing and eventual income tax raid U-turn.

In the briefing, she said she would be forced to raise income tax.

The next week, she scrapped plans to raise income tax.

Sources claimed this was because "the facts had changed" because of an upgrade from the OBR.

But the OBR said it had not issued a different forecast between the briefing and the U-turn.

The Treasury has said: "We're not going to get into the OBR's processes or speculate on how that relates to internal decision-making.

"The Chancellor made her choices to cut the cost of living, cut hospital waiting lists and double headroom to cut the cost of our debt.

"It's important to preserve a private space for Treasury-OBR policy and forecast discussions, so we welcome the OBR's confirmation that this will not become usual practice."