In a much anticipated speech later today, she's expected to say Britain is preparing for a "hard Brexit" if it doesn't get concessions from the EU on controlling immigration
Theresa May will delight Brexiteers and dismay Remainers by pledging a clean break from the EU in her long-awaited speech spelling out her Brexit strategy.
Unveiling a 12-point plan for Brexit, she will propose a "new and equal partnership" between an "independent, self-governing Global Britain" and its friends and allies in the EU.
And in her clearest statement yet on Brexit, she will declare: "Not partial membership of the European Union, associate membership of the European Union, or anything that leaves us half-in, half-out.
"We do not seek to adopt a model already enjoyed by other countries. We do not seek to hold on to bits of membership as we leave.
"The United Kingdom is leaving the European Union. My job is to get the right deal for Britain as we do."
The PM's speech comes after No 10 officials expressed delight at Donald Trump's pledge at the weekend to work to secure a rapid trade agreement with the UK after Brexit.
The Chancellor, Philip Hammond, also suggested at the weekend that Britain could cut taxes to create a corporate tax haven if the EU fails to provide it with an agreement on market access after Brexit.
And Mrs May's "half-in, half-out" remarks appear to confirm that she will announce that the UK is prepared to leave the single market, the European Court of Justice, and probably the customs union as well.
She will say leaving the EU presents the UK with an opportunity to build a stronger economy and a fairer society by embracing genuine economic and social reform – and an opportunity to build a brighter future for the country’s children and grandchildren.
"A little over six months ago the British people voted for change," she will say.
"And they did so with their eyes open: accepting that the road ahead will be uncertain at time, but believing that it leads towards a brighter future for their children - and their grandchildren too.
"And it is the job of this Government to deliver it. That means more than negotiating our new relationship with the EU. It means taking the opportunity of this great moment of national change to step back and ask ourselves what kind of country we want to be.
"My answer is clear. I want this United Kingdom to emerge from this period of change stronger, fairer, more united and more outward-looking than ever before.
"I want us to be a truly Global Britain - the best friend and neighbour to our European partners, but a country that reaches beyond the borders of Europe too.
"I want Britain to be what we have the potential and ambition to be: a great, global trading nation that is respected around the world and strong, confident and united at home."
And she will repeat her message that although the UK is leaving the European Union, it is not leaving Europe.
"The decision to leave the EU represents no desire to become more distant to you, our friends and neighbours."We will continue to be reliable partners, willing allies and close friends. We want to buy your goods, sell you ours, trade with you as freely as possible, and work with one another to make sure we are all safer, more secure and more prosperous through continued friendship."
On her plan for Brexit, the Prime Minister will says she has 12 negotiating priorities driven by four key principles:
Brexit and Ireland
Taoiseach Enda Kenny spoke to Mrs May by phone last night about her plans, outlining Ireland's concerns regarding Brexit, including issues around trade and the border with Northern Ireland.
The Taoiseach is reported to have stressed the importance of considering Northern Ireland in upcoming talks on Brexit, as well as both leaders calling for a "respectful" election campaign in Northern Ireland.