Relations between Canada and the U.S. are coming under serious pressure — and that has some commentators offering an unlikely — though not impossible — solution.

What if Canada joined the European Union?

Even before U.S. President Donald Trump threatened Canadians with "economic force" if they did not want to become a "51st state," Stanley Pignal, a columnist with The Economist, floated the idea of the country switching teams.

"As it turns out," he wrote, "both Europe and Canada may be in the market for upgraded alliances."

Pignal's column in early January was followed by a small flurry of online excitement: A former spokesperson for the Canadian Embassy in Paris endorsed the idea, as did one head of Britain's pro-EU movement. Even a former German foreign minister seemed to jump on board.

"Joke, rant, real proposal? It's hard to tell," read one column in the Montreal daily La Presse. "[But] with an American president now outright hostile to Canada, a rapprochement with Europe would be far from senseless."

But could it really happen?

Is joining the EU possible?

Article 49 of the Treaty on European Union opens membership to "any European state which respects and is committed to promoting human dignity, freedom, democracy, equality, the rule of law and respect for human rights, including the rights of persons belonging to minorities."

What it doesn't do is define European. 

"What constitutes a European country is left to political decision-making," said Dimitrios Argyroulis, a researcher at the Institute of European studies at the Université Libre de Bruxelles in Belgium.

A country outside Europe has only tried to join once before. In 1987, Morocco was rejected on the basis that it was not a "European country."

But Canada may be different. In his column, Pignal relies on the idea that Canadians are "honorary Europeans" on account of their "shared values" — something both governments have frequently highlighted. 

Canadians, they say, are generally likely to support gun control, oppose the death penalty and back a strong welfare state that regulates the free market — much like Europeans.

Canadian political and legal institutions are also modelled on European precedents, and more than half of Canadians identify as European in ancestry.

There could also be some perks for both sides to a closer union. As Pignal suggests, Canada could offer the EU access to vast reserves of strategic resources much rarer on the continent, like rare earth minerals and fossil fuels.

Canada, meanwhile, might benefit from access to Europe's large and skilled labour market — and reduce its dependence on the U.S. and its volatile politics.

"Ottawa must prepare for a world where Washington is less reliable," said Teona Lavrelashvili, a visiting fellow at the Martens Centre, an EU think-tank in Brussels. "Strengthening engagement with Europe … is not just strategic, but essential."

Could it actually happen?

So it's legally possible, and even has some upsides — but is it actually likely?

Don't hold your breath.

"It's not going to happen," said Steven Blockmans, a senior fellow at the Center for European Studies in Brussels.

The European Union already has a long waiting list: 10 candidates, including some, like Bosnia-Herzegovina, that have been waiting for decades.

"Think of the optics," said Maria Garcia, a senior lecturer in politics at the University of Bath in England. "If you've got very delayed candidacies … with these eastern countries that are actually in Europe, can you really open it up to countries outside it?"

A recent survey from the Martens Centre found just 38 per cent of EU residents want more members — and more than 80 per cent said they should come from inside Europe.

As Europe adds more members, it also gets harder to find agreement among them on who should be let in. Those decisions — along with policies on touchy subjects like security and immigration — are made by consensus.

"They're having a hard time keeping it together as it is," said Ruben Zaiotti, director of the Jean Monnet European Union Centre of Excellence at Dalhousie University in Halifax. "So envisioning further expansion — beyond those already lined up — I don't see enough energy to achieve that goal, or even to start the process."

More co-operation?

More likely than full membership for Canada, Zaiotti said, is "an advanced form of co-operation."

According to Michael Emerson, a former EU ambassador to Russia at the Centre for European Policy Studies in Brussels, that could take the form of "a maximal deepening of the relationship on all accounts: political, economic, cultural and security."

Or the EU could seek to create whole new alliances. 

"One could imagine a … loose multilateral grouping of the like-minded, without the U.S.," Emerson wrote in an email. "Then all democratic Europe, plus the rest of the non-U.S. OECD, might develop a collective diplomatic stance, asserting 'our' model of an enlightened West."

The EU already has some capacity to establish this kind of relationship. Its concept of the "European neighbourhood" allowed it to enter into resource-sharing partnerships with Armenia and Tunisia that go beyond typical trade agreements.

Some states, like Norway, are members of the European Economic Area, a free trade bloc, without being members of the EU. Others are full members but not part of the Schengen Agreement, which allows visa-free travel, or the Eurozone, which shares a currency and central bank.

Canada already participates in Horizon Europe, an EU-funded research grant program worth more than $140 billion, alongside other non-European states like New Zealand. 

"It signals a new chapter in our relationship with the EU," said François-Philippe Champagne, Canada's science minister, when signing the agreement last year.

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EU President Ursula von der Leyen, meanwhile, minced no words about the benefits for Europe. Canada is "the only country in the Western hemisphere with all the raw materials required for lithium batteries," she said — a key strategic resource as Europe shifts to green technology. "So I would say that this is a perfect match."

In this way, at least, European leaders appear open to expanding the definition of Europe — creating "a European onion, instead of a European Union," as Blockmans puts it.

"If there is any shift in EU thinking, it would likely be toward deepening [these] strategic partnerships rather than reimagining the EU as a geographically unlimited alliance," said Lavrelashvili.

You don't pick your friends

Of course, "it's still going to be very difficult for Canada … to separate themselves from America," Garcia said.

Its biggest trading partner cannot be replaced overnight — nor would defending Canadian (or European) territory be easy without American support.

"Europe is not a full substitute for the United States," Lavrelashvili said.

That's if Canadians want a substitute. 

Robert Finbow, deputy director of the Jean Monnet Centre at Dalhousie, said Canada's provinces seldom agree on EU priorities like climate or agricultural policy — with some seemingly reluctant to challenge Trump in a trade dispute.

Canadian businesses, meanwhile "have always relied on that ready [American] connection for profitability, and rarely taken alternate partners seriously enough," he said.

There's also the risk that any move to deepen ties with Europe could provoke more American aggression.

"It would increase their feeling that the EU is an antagonist and adversary, not an ally," said Argyroulis. "Just imagine the feeling of those people who are obsessed with border control to realize that they might share borders with the European Union."

There's another problem, too. If Canada was looking to Europe to escape from Trump-style politics, it might be barking up the wrong tree.

Later this month, there will be elections in Germany, a key EU member state, where the far-right, Elon Musk-endorsed Alternative for Germany (AfD) party has been moving up in the polls.

Germans are only joining voters in Italy, Austria, Belgium, the Czech Republic, Hungary, Finland, Poland, Norway, the Netherlands and France, who have granted Trump-style politicians public support or key power positions in government over the past few years.

"Canada can no longer take its close ties with Europe for granted," said Lavrelashvili.

All to say, Canadians and Europe may have some shared values — but in this new political era, Europe and Trump may share more values still.