Following the reveal of the Autumn Statement, Phillip Hammond and the Office for Budget Responsibility have endured a backlash by senior Tories over damning assessments about the economic impact of Brexit.
Independent financial experts will soon deliver their concensus on whether Philip Hammond was right to abandon plans to achieve a budget surplus by the end of the decade because he revealed the country is set to take a hit of almost £60 billion over the next five years as the UK leaves the European Union.
The Chancellor outlined how the Office for Budget Responsibility had slashed growth forecasts and predicted higher than previously expected borrowing as a result of the Brexit vote.
Iain Duncan Smith, a leading Leave campaigner, blasted the chancellor for this, calling it "another utter doom and gloom scenario" by an organisation "that simply hasn't got anything right".
He told the Daily Telegraph: "The key thing is that the OBR has been wrong in every single forecast they've made so far.
"On the deficit, on growth, on jobs, they've pretty much been wrong on everything."
Conservative MP Jacob Rees-Mogg called their assumptions "lunatic" and likened the OBR to "soothsayers" in an interview with the BBC.
He told Newsnight: "Until the Government has developed its negotiating strategy and explained it, the OBR can only operate on a status quo assumption.
"So they are perfectly rational in what they are doing, but it is not what the reality will be. Experts, soothsayers, astrologers are all in much the same category."
Rallying to the defence of the OBR, the former Labour leader, Ed Miliband, slammed Leave campaigners for bashing the watchdog.
He said: "Now Brexiteers attack OBR. They can't win argument for hard, destructive Brexit based on truth so have to try and win based on fantasy."