Liam Fox will call on David Cameron to show "political courage" as the Conservatives move towards the next general election, in the first sign of dissent since yesterday's policy shake-up in No 10.
The former defence secretary, now viewed as a standard-bearer for right-wing Tories within the parliamentary party, will use a speech to business leaders in Birmingham to make the case for a change of tack, the Guardian reports.
Fox, who attended Margaret Thatcher's funeral earlier this month, will use the spike of enthusiasm for the Iron Lady's approach to politics to call for a return to a similar approach today.
"Many people in this country will also have been reminded why they were drawn to the Conservative cause under Margaret Thatcher's leadership," he will say.
"Their values have not changed and neither have ours but we are currently lacking the language to reconnect with them.
"We are their natural home and they are our natural supporters, regardless of what background or part of the country they come."
Cameron hopes to have allayed such criticisms by establishing a new advisory 'policy board' consisting of troublemaking Tory MPs into Downing Street, headed by Orpington MP Jo Johnson who becomes the new head of policy in No 10.
Fox's call for more "intellectual creativity", deemed essential for the Conservatives to show if they are to win power in 2015, puts the Tory right's reception of the new arrangements into doubt, however.
"Jo Johnson is seriously intelligent and well-informed and he understands the European problem very well," leading Conservative eurosceptic Bill Cash told the Telegraph.
"But he believes the answers to problems like our trading relationships is the EU, and I do not agree.
"I have enormous regard for him, but Jo thinks that Europe and the single market are the way to go. I do not and nor do a lot of colleagues."
One senior Conservative told the Mail: "I love Jo Johnson, but when will Dave realise it's leadership we want, not go-betweens."
Another Tory told the Guardian: "The new policy board does look a bit lefty. Some say it is all about divide and rule."
Fox will undermine Cameron's leadership further by underlining Thatcher's appeal across different social classes. Both the prime minister and Johnson went to Eton.
"She powered into a meritocratic era, determined to ensure that wealth and ownership were not the preserve of a privileged few," Fox is expected to add.
The changes in No 10, which have also seen former energy minister John Hayes appointed to a new post as senior parliamentary adviser, leave the position of the backbench 1922 committee in doubt.
Its members would have preferred Hitchen and Harpenden MP Peter Lilley, a veteran of the Thatcher years, to have got Johnson's job.
I’ve been meeting with my new policy board, made up of MPs. I told them I want more ideas to help hardworking people twitter.com/David_Cameron/…— David Cameron (@David_Cameron) April 25, 2013