Boris Johnson will warn derailing Brexit would be a “disastrous mistake” as he claims some Remain supporters are more determined than ever to stop Britain quitting the European Union.
The Foreign Secretary will insist leaving the bloc is a cause for hope not fear as he gives a speech in central London setting out aims for uniting the country as exit day grows closer.
Mr Johnson is also expected to warn that having to adhere to EU directives would be “intolerable” and “undemocratic”.
He will say Remainers should not be told to “get over it” because many have “noble sentiments”.
To make Brexit a success, supporters must “reach out to those who still have anxieties”, he will urge.
But opponents pointed to his campaigning methods during the referendum and accused him of “hypocrisy of the highest order”.
Labour’s Chuka Umunna accused Mr Johnson of hypocrisy (Lauren Hurley/PA)
Mr Johnson will say: “I fear that some people are becoming ever more determined to stop Brexit, to reverse the referendum vote of June 23 2016, and to frustrate the will of the people.
“I believe that would be a disastrous mistake that would lead to permanent and ineradicable feelings of betrayal. We cannot and will not let it happen.
“But if we are to carry this project through to national success – as we must – then we must also reach out to those who still have anxieties.
“I want to try today to anatomise at least some of those fears and to show to the best of my ability that they are unfounded, and that the very opposite is usually true: that Brexit is not grounds for fear but hope.”
Writing in the Sun ahead of the speech, Mr Johnson said: “So much of this is about confidence and national self-belief.
“We Brits love to run ourselves down. In fact, one of the many ways in which we lead the world is in the sport of national self-deprecation.
“But when the history books come to be written, Brexit will be seen as just the latest way in which the British bucked the trend and took the initiative — and did something that responds to the needs and opportunities of the world today.”
The speech is the first of six being made by Prime Minister Theresa May and senior Cabinet figures to set out the Government’s road map for Brexit.
Brexit Secretary David Davis, International Trade Secretary Liam Fox and Mrs May’s deputy David Lidington are expected to speak in the coming weeks.
It follows criticism of the Prime Minister for failing to spell out Britain’s Brexit aims.
Chancellor Philip Hammond, a prominent Remainer who is not on the list of set piece speeches, is on a tour of European capitals aimed at building business and political ties.
Philip Hammond is on a tour of European capitals (Toby Melville/PA)
Officials said Mr Johnson would use his speech to set out plans for an outward-facing and liberal country.
He will say: “It is not good enough to say to Remainers – you lost, get over it; because we must accept that many are actuated by entirely noble sentiments, a real sense of solidarity with our European neighbours and a desire for the UK to succeed.”
Extracts briefed to The Daily Telegraph suggest Mr Johnson will insist it is only by “taking back control” of laws that UK firms will have the freedom to innovate.
Having to abide by EU directives would “be intolerable, undemocratic, and would make it all but impossible for us to do serious free trade deals,” he is expected to say.
Labour’s Chuka Umunna, who supports the Open Britain campaign against a hard Brexit, accused Mr Johnson of hypocrisy.
He said: “Boris Johnson is totally unqualified to preach about the perils of fear and betrayal when he engaged in disgraceful scaremongering with his ridiculous assertion that Turkey was on the verge of joining the EU and he has already betrayed millions of people by going back on his pledge to secure £350 million extra per week for the NHS.
“This is hypocrisy of the highest order. He has so far failed to explain why he is campaigning in Cabinet to take the UK out of the customs union when there is no other solution to the Irish border issue and it will jeopardise the Good Friday Agreement settlement.
“He has failed to explain why the Government has failed to start negotiating new trade deals when the campaign he led promised we would do so immediately after the Leave vote.”