The PM has so far been careful not to break with the EU on key policies. Now the US president could force his hand

Boris Johnson will sit down for breakfast on Sunday morning with a man he once famously described as “betraying a quite stupefying ignorance that makes him frankly unfit to hold the office of president of the United States”.

Not too long after Johnson made that remark, Donald Trump went on to win that office. And today Johnson – having defied similar assessments of his own fitness for the highest office – will come face to face with him at the Hôtel du Palais in Biarritz, on the sidelines of the G7 summit, in his first major event on the international stage as prime minister.

Both men rose to the top by portraying themselves as outsiders who were prepared to break some furniture in pursuit of an imagined national greatness. Now they must rearrange that furniture, or make some of their own.

Johnson flew into Biarritz after meetings with his counterparts in Berlin and Paris, meetings which appear to have brought them no closer to a Brexit deal.

At the three-day summit in Biarritz, amid the grandeur of the historic seaside resort on France’s Atlantic coast, the prime minister will be under particular scrutiny. Every word and gesture from Johnson at this annual gathering of the world’s major industrial democracies will be analysed for clues as to where he intends to position the UK on the gaping transatlantic divide between the US and Europe.

If the past is any guide, the prime minister will try to avoid giving away that location, and if Trump has an interest in helping him, he will not put on him on the spot when it comes to issues and instincts on which the UK has thus far been on the European side.

Those pivotal issues include UK support for the 2015 nuclear deal with Iran; backing for the Paris climate accord and acknowledgement of the urgency of the climate crisis, particularly against the blazing backdrop of the Amazon wildfires.

Facebook Twitter Pinterest Donald Trump and French president Emmanuel Macron at lunch before the G7 summit in Biarritz on Saturday. Photograph: Carlos Barría/Reuters

The UK has maintained its support for an international rules-based system with multilateral institutions and free trade at its centre. It has promoted a two-state solution for Israel and Palestine and a rejection of both occupation and annexation of Palestinian territories. Britain has also maintained a firm line over the Russian military intervention in Ukraine and Moscow’s annexation of Crimea, denying Russia readmission to the G7 club until it reverses those actions.

These are all shibboleths of the liberal international order, and they are being challenged daily by the Trump administration. Would a no-deal Brexit mean that Britain felt under pressure to do the same?

Since taking over as prime minister, Johnson has stuck to the consensus European script on all these critical foreign policy issues.

He has restated his faith in the nuclear agreement and the need to defuse tensions in the Gulf, rather than tighten the US stranglehold on Iran.

Johnson has also warned against the dangers of trade wars, in the face of Trump’s worsening face-off with China, and he has stuck to European orthodoxy on the need to preserve the Paris accord on climate, and to build on it.

Any substantial deviation at the G7 summit from such entrenched, shared positions would mean Johnson risking the toxic label of “poodle”, which his predecessor Tony Blair never managed to shake off.

The Labour leader, Jeremy Corbyn, is already framing Johnson as a “Trump first” prime minister, and there will be plenty of jilted European partners on hand to draw attention to British humiliation.

Emmanuel Macron, when asked last week if he thought that Johnson and Trump would team up together in a united front against other Europeans at the G7, played on deep British fears about the future.

Facebook Twitter Pinterest European Council president Donald Tusk warned Johnson he risked going down in history as ‘Mr No Deal’. Photograph: Christian Hartmann/Reuters

“I don’t think it’s Boris Johnson’s project or the British people’s project, as Britain leaves the EU saying it wants a bigger space in the world, to then become the junior partner of the US,” the French president told reporters last week.

He said any future trade deal between the US and the UK would not make up for the UK’s geographical and strategic links to Europe, and a trade deal with the US could come at a high price for Britain: a “historic vassalisation” to the US.

It is unlikely Macron chose his words carelessly. Johnson first signalled his break from Theresa May at the end of 2017 by warning that the UK must not become a “vassal state” of Europe. With the EU, the UK had one of the bigger seats at the table, but in the absence of a withdrawal agreement with Europe, Britain approaches the US as a junior partner at best, a supplicant at worst.

Johnson has insisted that he will defend British agriculture and the National Health Service against the predations of US corporations, but that will be harder if the UK crashes out of the EU without a deal, a course of action Trump and his administration have repeatedly advocated. Johnson’s readiness to embrace such an outcome distinguishes him from Theresa May, and is arguably the most important reason Trump openly preferred him to his predecessor.

On this issue at least, Johnson has, with his brinksmanship, placed himself closer to Trump and further from the EU. The European Council president, Donald Tusk, drily noted that when he meets Johnson on Sunday, he will be the third Tory prime minister with whom he has sat down to discuss Brexit. He warned Johnson on Saturday that he risked going down in history as “Mr No Deal”.

On the way to Biarritz, Johnson sought to defend his strategy of blaming Britain’s EU partners for failing to come up with a solution to the Irish backstop impasse.

“I don’t want a no-deal Brexit but I say to our EU friends if they don’t want no deal they have got to get rid of the backstop from the treaty,” Johnson told reporters. “If Donald Tusk doesn’t want to go down in history as Mr No-Deal Brexit, then I hope this point will be borne in mind by him too.”

Trump, ironically for a self-proclaimed master of the deal, can be expected to continue to pull in the other direction, seeking to persuade the prime minister that “Mr No Deal” would be a badge of pride.

In the absence of specifics, both Trump and Johnson will seek to play up the manly bonhomie of a renewed “special relationship”. The US president will want to show he has at least one friend in Biarritz, the man he proudly referred to as “Britain [sic] Trump”, and has shown that he is prepared to overlook past slights in special circumstances.

For his part, Johnson – who declared only a few years ago that the only reason he would avoid some parts of New York was “the real risk of meeting Donald Trump” – must seek to show he can connect more successfully with the US president that his hapless predecessor.

Facebook Twitter Pinterest Johnson with Canadian PM Justin Trudeau in France on Saturday. Photograph: Jeff J Mitchell/Getty Images

Both men will paint a rosy picture of a future US-UK trade deal, because the ugly reality of the negotiations can be put off until later. At some point post-Brexit, the UK will have to make a decision on whether its regulatory standards are to converge with the US or with the EU.

It cannot do both. Converging with the US would be likely to involve breaking promises about British food, agriculture and animal welfare as well as the National Health Service.

Moreover, any trade deal with the US would have to gain approval from Congress, and the House of Representatives will be in no mood to cooperate if Brexit has an impact on the Good Friday peace agreement in Northern Ireland. The Democratic speaker of the House of Representatives, Nancy Pelosi, has repeatedly said there is “no way whatsoever” a US-UK free trade deal would be approved if Brexit affected the border between the two Irelands.

So whatever the upbeat noises about future trade Trump and Johnson make on Sunday, it will mean little in real terms. The rest will be mood music, and Johnson has shown himself adept in that department. The G7 is a big stage, but not a particularly challenging act. There are set scripts and orthodoxies to follow.

But as ever, Trump is the wild card, constantly threatening to upset the comfortable western consensus of years past. If he so chooses, the president could set the rejuvenated special relationship with the man he has frequently called his friend, and force Johnson to make the hard choices he is hoping to postpone until after an election.