Former British health secretaries Jeremy Hunt and Sajid Javid have both pledged to slash corporation tax as they announced separate bids for the Tory leadership.
It comes after two serving Cabinet ministers, Chancellor Nadhim Zahawi and Transport Secretary Grant Shapps, revealed their intention to run for the top job within an hour of one another.
Declaring their candidacies in The Telegraph, Mr Hunt and Mr Javid both said they would not only scrap the former chancellor's plans to raise corporation tax from 19% to 25% in April, but reduce the rate to 15%.
Mr Zahawi, Rishi Sunak's successor, had said earlier this week that "everything is on the table" when questioned over the tax rise.
The leadership contenders' timescales for the change are different, with Mr Hunt slashing the tax to 15p in his first autumn Budget, while Mr Javid would set a "glide path".
Mr Javid also said he would scrap the British government's controversial national insurance hike, bring forward the planned 1p income tax cut to next year, and introduce a further "significant" temporary reduction on fuel duty.
The pair spelled out their economic plans in separate interviews with the newspaper.
Foreign Secretary Liz Truss will launch a bid to become next Conservative leader by pledging that she will advocate "classic Conservative principles", the Mail on Sunday reported.
The newspaper said she will reverse the government's national insurance rise, cut corporation tax and introduce measures to ease the cost- of-living crisis when she announces her campaign, possibly on Monday.
Launching his campaign, Mr Zahawi pledged to lower taxes for individuals, families and business, boost defence spending, and continue with education reforms that he started in his previous role.
Mr Zahawi, a former education secretary, was the third serving government minister to kick off their campaign for the leadership, after Mr Shapps and Attorney General Suella Braverman declared their intentions.
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Earlier, Defence Secretary Ben Wallace said that after "careful consideration" and discussion with colleagues and family, he would not stand to be party leader and the next prime minister.
In addition to Mr Zahawi, Mr Shapps, Mr Sunak, and Ms Braverman, ex-minister Kemi Badenoch and senior Tory Tom Tugendhat have launched their own bids, with further announcements anticipated over the coming days.
Trade Secretary Anne-Marie Trevelyan is the first Cabinet endorsement for Tom Tugendhat as Conservative leader, the Sunday Times reported.
Trade minister Penny Mordaunt is included among other potential front-runners.
It was reported on Saturday that Boris Johnson intends to stand down as prime minister on Monday in order to run again for Tory leader.
But this suggestion was knocked down by a spokesperson for Mr Johnson as completely untrue.
Tory MP Mark Francois has said he believes at least 12 people will put their names forward.
Ms Badenoch announced her campaign in The Times, with a plan for a smaller state and a government "focused on the essentials".
She is backed by Lee Rowley, the MP for North East Derbyshire, and Tom Hunt, the MP for Ipswich.
Former minister Steve Baker has thrown his support behind Ms Braverman's bid, despite previously saying he was seriously considering putting himself forward for the top job.
Those publicly backing Mr Sunak include Commons leader Mark Spencer, former Tory Party co-chairman Oliver Dowden, former chief whip Mark Harper, ex-ministers Liam Fox and Andrew Murrison, and MPs Bob Neill, Paul Maynard and Louie French.
Other potential contenders have also received endorsements from Tory ranks, despite not yet launching a bid of their own.
MPs Chloe Smith, Julian Knight and Jackie-Doyle Price have backed Ms Truss, while Gosport MP Dame Caroline Dinenage has declared her support for Ms Mordaunt, and former ministers Chris Philp and Rachel Maclean have said Mr Javid would be their choice for PM.
The leadership bids to date have coincided with some controversy over the appointment of new ministers to Mr Johnson's caretaker Government.
Mr Sunak announced his bid for leader on Twitter on Friday afternoon, saying: "Let's restore trust, rebuild the economy and reunite the country."
The absence of a clear front-runner in the leadership race has tempted a number of less-fancied contenders to step forward, with backbencher John Baron saying he will be "taking soundings" over the weekend.
Tory MP and newly-appointed minister Rehman Chishti also confirmed on Saturday he is "actively considering" running for the post.
As candidates have started to make their move, Tory MP Charles Walker said it is incumbent on those running for leader that they "don't knock lumps out of each other".
Following elections to the executive of the backbench 1922 Committee on Monday, the new body will draw up a timetable for the leadership election.
