Johnson said the European Union's plan "to construct what is effectively a single polity out of 27 countries" - set out in some detail by the President of the European Commission recently - "is simply not for Britain".
British Foreign Secretary Boris Johnson has fueled speculation that he hopes to eventually succeed Prime Minister Theresa May by spelling out his Brexit goals days before her major policy speech on the topic.
"My friends, I must report that there are at least some people who are woefully underestimating this country", Johnson wrote in the Daily Telegraph. They think Brexit isn't going to happen.
But today he said: "This country will succeed in our new national enterprise, and will succeed mightily".
"We have a glorious future".
Johnson making his own views known first may be seen by many as a challenge to her authority, which has been weakened by a poor result in the June 8 election that cost her Conservative Party its majority in Parliament.
Instead, he publicly pledged his loyalty.
Johnson also leaves aside question of "bill" of divorce from EU, rights of european immigrants or future of border of Ireland: three great obstacles that stand in negotiations with Brussels.
"We would not expect to pay for access to their markets any more than they would expect to pay for access to ours", he wrote. The article made no reference to a transition period the government is expected to negotiate.
In the article for the Telegraph, however, he said the United Kingdom would "roughly" be £350 million better off and it would be a "fine thing" if a lot of it went on the health service.
Labour's Chuka Umunna, leading supporter of Open Britain, which is campaigning for continued single market membership, said: 'Boris Johnson had a chance to vote to deliver the £350 million extra a week for the NHS in February, and he refused to do so.
In the Telegraph, Mr Johnson said once the United Kingdom had "settled our accounts.it would be a fine thing. if a lot of that money went on the NHS".
Will Tanner, a former adviser to the Prime Minister, tweeted it was "astonishing" that Johnson thought "this self-serving posturing, disloyal at best of times, would reflect well in the hours after a terror attack". "The real PM *just* raised threat level".
"Meanwhile guy who wants to replace her issues a prelude to resignation, to save face over £350m".
She is expected to give an update on Brexit negotiations and "will underline the government's wish for a deep and special partnership with the European Union once the United Kingdom leaves the EU", the prime minister's spokesman said.