Mid Bedfordshire MP Nadine Dorries has launched a furious attack on George Osborne, branding him "stupid" and accusing him of lying about her.
The Tory backbencher said the Chancellor was "out of his depth" and a "pernicious influence" on the economy and David Cameron.
Speaking to Huffington Post UK, Ms Dorries admitted that there was a "personal element" to some of her criticisms after the Prime Minister jibed that she was "extremely frustrated" in the Commons last year.
She said her animosity to Mr Osborne stemmed from his role in defeating a parliamentary amendment designed to restrict abortion counselling.
Repeating her call for the chancellor to be replaced, Ms Dorries said: "I think George Osborne is out of his depth. He might be a politician and a strategist and a political campaigner. I don't think he's up to the job of being chancellor."
The backbencher blamed the expected collapse of boundary reforms, which many believed would have benefited the Tories, on Mr Osborne's "stupidity and arrogance".
"We won't win an election while George Osborne is in a key position in the Conservative Party," she said. "I think George Osborne is a pernicious influence on the economy, on our political strategy, on our campaigning, on David Cameron personally and on the Number 10 operation."
In May, after Ms Dorries referred to the prime minister and the chancellor as "two arrogant posh boys", Mr Osborne told the BBC's Andrew Marr show: "Nadine Dorries, for the last seven years, I don't think has agreed with anything either myself, David Cameron or indeed most Conservatives in the leadership of the party have done."
But the MP insisted: "Osborne lied when he said that. Osborne and I have worked together for years. We worked together in Oliver Letwin's office for three years, from 2001, when I wasn't an MP, and I got to know George Osborne quite well. And that was a lie. It was just a lie."
Ms Dorries said she expected a Tory leadership contest before the next general election in 2015, suggesting colleagues would seriously consider ditching Mr Cameron as the threat to their own seats became more real.