A former key aide of Theresa May has launched a strongly worded attack on Chancellor Philip Hammond's abilities ahead of next week's Budget.
Nick Timothy, who quit as the Prime Minister's joint chief of staff following the Conservatives' poor general election showing in June, said Mr Hammond lacks the desire to change lives for the better.
The comments come after a spate of reports claiming there is growing tension between the PM and Mr Hammond.
Writing in The Sun, Mr Timothy stated: "I fear Philip Hammond's instinct is to maintain existing policy, regardless of its quality.
"This must not be mistaken for conservatism. Nor is it down to a careful analysis that concludes the status quo is best.
"I worry it is because the Chancellor lacks a burning desire to change people's lives for the better, and the imagination to see possibilities beyond how the world works today."
Mr Timothy was scathing about Mr Hammond's past performance, writing: "In his first Budget, Hammond got it all wrong.
"Concerned that the rising number of people in self-employment was reducing tax receipts, he increased their National Insurance Contributions.
"Theresa May warned him repeatedly that he was making a mistake, but the Chancellor insisted on going ahead and the inevitable occurred.
"Conservative MPs rebelled and he dropped the policy and the tax receipts that came with it."