Liz Truss will set out her pitch to become prime minister with a pledge to “level up in a Conservative way” and cut taxes.
The Foreign Secretary has the support of Boris Johnson’s remaining loyalists in the Tory leadership race that will select his successor.
She secured her place in the next round of the contest by nabbing the third-highest number of votes in the first ballot of Tory MPs on Wednesday, behind rivals Rishi Sunak and Penny Mordaunt.
Ms Truss’s backers have been accused of running a campaign to damage Mr Sunak’s chances in the contest, criticising the former chancellor’s “economically damaging” policies.
In a campaign speech on Thursday, Ms Truss will detail her economic plan, which includes reversing April’s National Insurance rate rise, lowering corporation tax and enacting supply-side reforms.
She is expected to say: “My mission is to make our country an aspiration nation, where every child, every person has the best opportunity to succeed.
“I have a plan to make Britain a high-growth economy through bold supply-side reform.”
The South West Norfolk MP will also refer to her education at a northern comprehensive school, where she saw children who “failed” due to “low expectations”.
“They will never be let down again on my watch.
“Everyone in our great country should be born with the same opportunities and be able to know that the town they are born in has opportunity”.
“My mission in politics is to give every child, every person, the best opportunity to succeed, and for their success in life to depend solely on their hard work and talents, not their background or where they are from.”
Despite being a Johnson loyalist, Ms Truss kept her powder dry as the Tory top brass turned on the mortally wounded Prime Minister last week, though she did cut short a foreign trip to Indonesia to head back to Westminster as he announced his resignation.
She confirmed long-standing expectations that she would throw her hat into the already crowded ring on Sunday.
The 46-year-old has made little secret of her leadership ambitions, with a series of high-profile interventions and photo opportunities in which she appeared to be channelling late Prime Minister Margaret Thatcher.
The former-Remainer-turned-ardent-Brexiteer’s hard line on Ukraine, insisting Russian forces must be driven from the country, and threats to tear up parts of the Northern Ireland Protocol with the EU play well with sections of the party.
After Wednesday’s vote, a spokeswoman for Ms Truss said she “has the experience to deliver the benefits of Brexit from day one, grow our economy and support working families”.
Chief Secretary to the Treasury Simon Clarke urged fellow Tory MPs to unite behind her “free market vision”.
In her speech, Ms Truss will highlight her experience, having worked across many Whitehall departments, and her aim to unite the party.
“I am ready to be Prime Minister on day one. I can lead, make tough decisions and rise to the moment,” she is expected to say.
“The British people are crying out for a united and modern Conservative Government ready with the courage of its convictions to deliver on its promises.”