The Tory race for Number 10 has begun in earnest as senior figures threw their weight behind Boris Johnson and Cabinet minister Stephen Crabb prepared to formally launch his rival campaign.
The Work and Pensions Secretary and Business Secretary Sajid Javid have teamed up in what Mr Crabb dubbed a "blue collar ticket" to take on Mr Johnson.
The former London mayor and Home Secretary Theresa May are viewed as favourites in the race to succeed David Cameron, with nominations due to open later.
Cabinet ministers Liz Truss and John Whittingdale, from either side of the European Union referendum divide, are reported to have pledged support to Mr Johnson.
The Brexit campaign frontman has also received the backing of Leave-supporting justice minister Dominic Raab and farming minister George Eustice, with dozens more Tory MPs expected to follow suit, The Sun reported.
Writing in the Daily Telegraph, Ms Truss, who backed the Remain side in the EU referendum, said: "Britain has achieved amazing things in the past and, with the right leadership, will do so again in the future.
"This leadership must now come from someone who believes in, and campaigned for, leaving the EU. The British people must be able to trust the new prime minister to deliver the instruction they have given. I do not think anyone who campaigned for us to stay in the EU would be able to secure that trust in the same way.
"That is just one reason why I am backing Boris Johnson to be the next leader of the Conservative Party and our next prime minister."
She also praised Michael Gove, the Brexit campaign chief, adding: "With him on Boris' team, I am convinced we can get a good deal for Britain."
Meanwhile, Education Secretary Nicky Morgan, who is considering a leadership bid, said the Tories had to make the "positive case" for immigration rather than be "pushed around" by Ukip leader Nigel Farage.
"We are part of an interconnected world." she said. "We have a proud tradition of giving refuge to people and inviting people over to work and man our essential services - there are 50,000 people from overseas working in our NHS. If you come across an immigrant in the NHS, they are more likely to be treating you than in front of you in the queue."
She told The Daily Telegraph: "The country is changing. It is the task of a government to lead that conversation and to say to people ' this is what is happening; this is how we are dealing with it', not be pushed around by the likes of Nigel Farage."
Mr Crabb has lined up Attorney General Jeremy Wright to act as the manager for his campaign.
Hugely popular among colleagues, Mr Crabb comes from the sort of ordinary background that chimes with many voters - and Mr Javid is the son of a Pakistani bus driver who became a highly successful investment banker.
Both men backed the Remain side although Mr Javid faced claims he was privately in favour of leaving the EU.
Nominations for the leadership will close at midday on Thursday, with the new Tory leader - who will also take the keys to Number 10 - expected to be in place by September 9.