Former British foreign minister Boris Johnson made what was seen as a blatant pitch to replace Prime Minister Theresa May as leader, damning her Brexit plans while calling for their party to regain its confidence.
The move is the latest setback for Mrs May in a week which has seen 1,500 activists at the party conference in Birmingham give a standing ovation to Boris Johnson after he declared her Brexit plans a "constitutional outrage".
The minister, who described himself as a "stubborn optimist", also used his speech to call for unity in his party, which has been increasingly divided since Prime Minister Theresa May announced the "Chequers agreement" - a roadmap for the post-Brexit relationship between the United Kingdom and European Union - in July.
The councillor for Stratford-Upon-Avon was reacting to Boris Johnson's conference speech, which she said was "full of substance".
Mr Johnson said: "If we cheat the electorate - and Chequers is a cheat - we will escalate the sense of mistrust".
'We must show everyone in this country that we are that party.
Ms May, when asked in a series of broadcast interviews earlier about Mr Johnson's expected intervention, said she had expected his speech would be a "lively" event but declined to make any personal criticism.
Mr Johnson's demand for the PM to "chuck Chequers" has echoed around the corridors and fringe meetings at a conference gathering riven by profound differences over the best approach to Britain's European Union withdrawal.
"Unfortunately, Mr Johnson seems to behave in a way that suggests he is only focused on his own self-interest and not on the interests of our country and I find that very disappointing".
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"And that means, instead of aping Corbyn, we have to take our basic Conservative ideas and fit them to the problems of today".
A United Kingdom cabinet minister has accused Boris Johnson of being "focused on his own self-interest and not on the interests of our country".
Mr. Johnson is a major figure in the party and esteemed by many Tories as a guiding light on Brexit.
"My fellow Conservatives, this is not democracy. We have that from Theresa May, I think there are others who would struggle to provide that type of leadership", Gauke said.
Mixing breezy jokes with biting one-liners that always stopped short of attacking May herself, the former foreign minister called her strategy "dangerous and unstable".
"That plan is Boris", Conservative lawmaker James Duddridge tweeted. "No, because I think we probably can't have the self-indulgence of a leadership challenge".
Brexit negotiations are at a "really critical point" and people should support the prime minister, he said.
"It was a great speech, he was optimistic, he talked about Conservative values, and he talked about the opportunities if we do Brexit properly", Richard Tice, co-chairman of campaign group Leave means Leave, said after Johnson's speech.
The BBC's political editor Laura Kuenssberg said it was the PM's task to show she could "change the conversation" and demonstrate that Brexit would make a positive difference to people's lives at a time when her future was an "open question" within the party.