Contenders to succeed David Cameron as Tory leader and prime minister are declaring their intention to stand.
With nominations to open later, Work and Pensions Secretary Stephen Crabb has said he will seek the leadership, promising a “One Nation” Conservatism.
Boris Johnson is reported to have the support of 100 MPs, and Home Secretary Theresa May is also expected to stand.
Education Secretary Nicky Morgan, who could also declare, said the “positive case” for immigration should be made.
Nominations for the contest will open on Wednesday evening, with candidates having until noon on Thursday to come forward.
The leadership race was triggered by Mr Cameron’s decision to stand down after the UK voted to leave the EU last week.
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All the prospective contenders are gauging support within the parliamentary party, which will whittle down the candidates to two in a series of ballots before Conservative party members decide between them. The final result is expected on 9 September.
The BBC’s political correspondent Carole Walker said the key issue in the campaign would be who could unify the party after the bruising EU referendum and set out a credible plan for a Brexit after Mr Cameron said he would leave the fraught and complex negotiations to his successor.
In a speech unveiling his candidacy, Mr Crabb said he could heal the “bad blood” in the party since the EU referendum, saying nobody else in his party had a “compelling answer”.
He said he was standing because following the EU referendum, “I really worry about the future of our divided United Kingdom”.
“We will enact the British people’s wishes on the EU,” he wrote in an article in the Daily Telegraph setting out his agenda.
“The verdict was clear; there is no going back. A second referendum is out of the question. What the country needs now is a clear direction, not further instability.”
Mr Crabb also said he would listen to the public’s concerns.
“This referendum has cast a harsh light on the deep economic and social divisions that still blight our country,” he said.
“People are stuck on low wages – even no wages – despairing at their hollowed-out town centres and a sense of being left behind in a fast-changing world.
“So my government will confront it, spreading economic and social opportunities to every corner of Britain in a way we haven’t seen before.”
Speaking to BBC Radio 4’s Today programme Mr Javid said he hoped to become chancellor, if Mr Crabb won the contest.
He said Mr Crabb had “absolutely what it takes” to ensure the UK becomes “stronger” and a “much more united country”.
Both Mr Crabb and Mr Javid campaigned for the Remain campaign, but the business secretary said “in some ways we are all Brexiteers now”, saying it was “all about delivery now”.
Mrs Morgan, the education secretary, told Radio 4’s Today she was “actively considering” running for the leadership,
She said the referendum result showed a “divided nation”, between “young and old, north and south” and said the party needed to unite the country and appeal to the centre ground of British politics.
“Of course we have to deal with the result from last week and the exit negotiations from the EU to get the possible deal for the British people, but we cannot have the next three and a half years until 2020 defined by just Europe,” she said.
Mrs Morgan, who supported Remain, also called on the Conservatives to have a “proper grown up debate” on immigration, saying there was “a positive case to be made for immigration” that was not often heard.
“It’s incumbent on politicians to make the case that it is not for blaming immigrants about jobs and housing. Actually, it is up to us to provide the solutions and support to people,” she argued.
Mr Johnson is regarded by many as the favourite at this stage, having been a leading figure in the victorious Leave campaign and being popular among Conservative activists who will make the final choice.
Having already won the backing of Justice Secretary Michael Gove, Mr Johnson is expected to announce he has got the endorsement of Environment Secretary Liz Truss, a prominent Remain campaigner. The Sun suggested he had won the backing of 100 MPs already.
Mr Johnson is expected to be advised by Lynton Crosby, the Australian strategist behind the Tories’ last general election campaign.
Also considering standing is John Baron – a backbench Eurosceptic who led the initial drive to hold an EU referendum. Health Secretary Jeremy Hunt and Energy Minister Andrea Leadsom are also weighing up leadership bids.