Outspoken Tory MP Nadine Dorries has launched a fresh attack on David Cameron, branding him patronising and sexist and challenged him to "spend more of his time being a Conservative".
In an interview with Tatler magazine, the mid-Bedfordshire MP also dismissed the Prime Minister as "a sheep in wolf's clothing" while praising his old rival Boris Johnson as a Tory who could reach out to ordinary voters.
Ms Dorries previously hit the headlines when she denounced Mr Cameron and Chancellor George Osborne as "arrogant posh boys who don't know the price of milk".
In her latest onslaught, she described the Prime Minister as "a sheep in wolf's clothing, a liberal Tory who should spend more of his time being a Conservative".
She indicated that she is still angry at his put-down of her at Prime Minister's Question's when he called her "frustrated".
She said: "It was a patronising, sexist thing to do, and that's not the act of a statesman or someone worthy of the position of Prime Minister."
The MP, who posed for a fashion shoot for the magazine standing on a table on the House of Commons terrace wearing a £1,299 Oscar de la Renta dress and a pair of Manolo Blahnik shoes, also had another go at the Chancellor.
"George Osborne is a Machiavellian who manipulates people and practises dark arts," she said.
Despite her criticisms of the party leadership, Ms Dorries insisted that she was not a natural rebel and had, in the past, held Mr Cameron in great affection.
"I've never been disloyal to this party until now. If you had asked me even 18 months ago: would you ever vote against your party? I would have said: no because the party is much bigger and more important than me. And because I felt great affection for Dave in a sisterly brotherly kind of way."
Amid intense speculation that Mr Johnson is positioning himself for a future Tory leadership challenge, she pointedly praised the London mayor.
"I love Boris. He reaches the parts that other politicians can't. And he had an office next to mine and I used to go and wake him up to make him vote," she said.
"But what's important is that he does more than speak inwards into Westminster. There are millions of people out there who need to know that there are ordinary people in Parliament. They've got this impression of us, and we've got a responsibility to break that image."
Ms Dorries is the latest Tory to speak out over Mr Cameron's leadership amid continuing unease within the party ranks as MPs prepare to return to Westminster on Monday following the summer break.
Former minister Tim Yeo challenged him to show whether he was "man or mouse", while fellow Conservative backbencher Brian Binley accused the Prime Minister of acting as "chambermaid" to his Liberal Democrat coalition partners.