Theresa May is to launch her bid to become Tory leader with a pledge to create a 'Brexit Department' to oversee the UK's divorce from the EU.
The Home Secretary is set to go head-to-head with Boris Johnson as nominations close today for the Conservative party's race to succeed David Cameron.
May, who is ahead of the former London Mayor in some early polls, vowed to appoint a senior 'Leave' MP to become Secretary of State for Brexit in a specially created Whitehall department.
Work and Pensions Secretary Stephen Crabb was the first to declare in the Tory race on Wednesday, but Johnson and May are both believed to have scores of MPs backing them.
Liam Fox, Jeremy Hunt and Nicky Morgan are considering bids too, as nominations close at noon.
Westminster insiders said that Fox - whose former aide James Heappey declared for Crabb - decided to run after May turned down plans for him to become her Foreign Secretary.
This follows reports that May had 'snubbed' a planned meeting with Boris Johnson to discuss a possible alliance.
A source close to May told HuffPost UK: "There will be no deals with anybody. There never will. She's in it to win it."
In her speech, May will declare that the EU referendum result means that the UK needs a proper, detailed plan but also a Government that heals the divides caused by Europe.
"We need a bold, new, positive vision for the future of our country - a vision of a country that works not for a privileged few but for every one of us," she will say.
May will declare that Britain is "he same outward-looking and globally-minded and big-thinking country we have always been - and we remain open for business and welcoming to foreign talent".
But the Home Secretary will also be clear about that the process of leaving the European Union will not be ‘brief or straightforward.’
"That means it is going to require significant expertise and a consistent approach," she will say.
"I will therefore create a new government department responsible for conducting Britain’s negotiation with the EU and for supporting the rest of Whitehall in its European work.
"That department will be led by a senior Secretary of State - and I will make sure that the position is taken by a Member of Parliament who campaigned for Britain to leave the EU."
The department would have its own Permanent Secretary and powers to liaise with other Whitehall departments.
At present, preparatory work is being done by a 'Brexit unit' operating within the Cabinet office, but it is relatively small and only has Oliver Letwin in charge.
Under May's plan, the new Department would be one of the most important in Govermnment.
"The job now is about uniting the Party, uniting the country and negotiating the best possible deal for Britain," she will say.
Johnson is said to have 100 MPs already behind him, and unlike May was the figurehead of the Leave campaign. She backed the Remain cause, but has since attracted Leave MPs to her leadership bid.
A new YouGov/Times poll out on Thursday gave May a big new lead among Tory party members, with the Home Secretary on 55% to Johnson's 38%.
One Tory MP told HuffPost that May was "ahead among members, contrary to popular belief that Boris is the darling of the membership".
But the former Cabinet minister, who will be backing Johnson, said that the inclusion of Michael Gove on the ticket would strengthen his chances considerably.