Liz Truss has been forced to defend her campaign after her allies turned their fire on her rival Penny Mordaunt, who has surged into second place in the Conservative leadership contest.
Lord Frost, the former Brexit minister who is expected to endorse Ms Truss within days, claimed that as his deputy Ms Mordaunt was missing in action and that he had asked that she be moved on after 6 months.
At her official campaign launch, Mr Truss was also challenged that her allies had been publicly critical of the frontrunner Rishi Sunak as well as claiming that Ms Mordaunt, who has less cabinet experience than her rivals, requires “stabilisers”.
The Foreign Secretary insisted that she was “putting forward a positive agenda” and that she would not make any "disparaging comments" about her rivals.
Trade minister Ms Mordaunt surprised many when she came second in the first round of voting, pushing Ms Truss into third.
Ms Mordaunt’s campaign has also gained momentum from opinion polling which shows she is the bookmakers’ favourite to become the next prime minister.
Supporters of Ms Truss highlighted a scathing attack on Ms Mordaunt from former Brexit minister Lord Frost.
He told TalkTV: "I am quite surprised at where she is in this leadership race. She was my deputy - notionally, more than really - in the Brexit talks last year.
"I felt she did not master the detail that was necessary in the negotiations last year. She wouldn’t always deliver tough messages to the European Union when that was necessary.
"She wasn’t fully accountable, she wasn’t always visible. Sometimes I didn’t even know where she was. This became such a problem that, after six months, I had to ask the Prime Minister to move her on and find somebody else to support me."
Ms Truss also stressed her loyalty to Boris Johnson as she defended her decision not to resign from his cabinet.
Ms Truss, who has picked up support from Mr Johnson’s remaining allies, rejected the suggestion that her decision not to turn on the prime minister would hurt her campaign.
She said: "I am a loyal person. I am loyal to Boris Johnson. I supported our Prime Minister’s aspirations and I want to deliver the promise of the 2019 manifesto.”
She also suggested she was the best candidate to win a future general election.
"There isn’t a great groundswell of support in the country for (Labour leader) Sir Keir Starmer or (Liberal Democrat leader) Sir Ed Davey,” she said.
"What the British people are crying out for is a modern and united Conservative Party, ready with the courage of its convictions to deliver on the promises that we have made."
