Justin Trudeau, Donald Trump's neighbour to the north, has a $500bn problem — how to keep Canada's most important economic relationship on track when he is at odds on so many issues with the new occupant of the White House.
There are many contrasts between the Canadian prime minister — a 45-year old self-declared feminist who campaigned an optimistic message of "sunny ways" — and the 70-year US president who won power on a platform of protectionism and immigration curbs.
In policy terms, potential flashpoints include the North American Free Trade Agreement, which Mr Trump blames for the loss of US jobs and which he has pledged to overhaul; immigration, with Canada pledging to admit 25,000 Syrian refugees this year; and climate change as Mr Trudeau looks to push through a carbon tax plan while Mr Trump reverses course in the US.
"Although Trump's actions in the past few weeks are what he said he would do, they still come as a shock," said Roland Paris, one of Mr Trudeau's top foreign policy advisers during his 2015 election campaign and first months in office.
The challenge for Mr Trudeau is to keep faith with Canadians — who largely disapprove of Mr Trump, according to recent polls — while preserving his country's $500bn annual trade relationship with the US.
"It is common sense" not to endanger the relationship, said Paul Frazer, former Canadian ambassador to the US.
The prime minister could only watch as Mr Trump fired off a barrage of executive orders, including a travel ban barring people from seven predominantly Muslim countries from entering the US. The ban, currently suspended pending litigation in the US courts, even raised questions about whether Ahmed Hussen, Ottawa's own immigration minister and a former Somali refugee, could still cross the two nations' shared 9,000km border.
Ties between the nations have been through rough patches before. The relationship between Stephen Harper, former Conservative prime minister, and then US President Barack Obama was chilly, while Mr Trudeau's father Pierre, a long-time Canadian premier, clashed with Richard Nixon.
But when Mr Trudeau took the helm, the countries entered a new era. Mr Trudeau and Mr Obama were an ideological fit, fuelling a bond that even the White House Instagram account labelled a "true bromance". With Mr Trump at the helm in the US, the relationship between the two countries has entered a new and far more turbulent phase.
Mr Trudeau will emphasise the value of the bilateral ties when he meets Mr Trump, which Sean Spicer, White House press secretary, said was likely to happen "very shortly". The Canadian prime minister has already begun a charm offensive, sending staff to meet Jared Kushner, Mr Trump's aide and son-in-law, and Steve Bannon, the president's chief adviser.
Mr Trump's antitrade rhetoric has focused more on Mexico and China, and if he does leave Nafta, the US and Canada have a separate trade agreement dating back to the 1980s. "So in some sense Canada approaches the renegotiation from a good position," said Max Cameron, professor at the University of British Columbia.
Mr Trudeau's challenge, said Mr Paris, is to hold his principles "without picking a fight with Trump". The premier knows how to cater to his domestic audience, Mr Paris said, pointing to his political performance after Mr Trump announced the travel ban. The prime minister swiftly tweeted a photograph of himself welcoming a young Syrian refugee at Toronto's international airport, earning widespread plaudits. The following day, in the aftermath of the mass shooting at a Quebec mosque, Mr Trudeau condemned the act as "terrorism on Muslims".
But he is under pressure from rivals including Tom Mulcair, leader of the leftwing New Democrats, and Rona Ambrose, interim Conservative leader, who are seeking to capitalise on Mr Trump's unpopularity.
Although his poll ratings have slipped, Mr Trudeau remains a historically popular prime minister. But "charm will only get you so far", warned Mr Frazer. "Something sudden will happen with Trump and Canadians will look to Mr Trudeau immediately and say: what are you going to do about it? And that day will come."