Here's why Americans should care about the Canadian election

The close race comes after a decade of leadership by Stephen Harper, whose relationship with Barack Obama has suffered. But a victory for Justin Trudeau and the Liberals on Monday could help the US and Canada forge renewed ties

America’s neighbour to the north will head to the polls on Monday for what looks likely to be a nail-bitingly close election .

Related: Canada election: will anti-Harper sentiment be enough to bring progressives to power?

The incumbent Conservatives, under Stephen Harper, have not been popular with the Obama administration, partly because they have lobbied the US hard to build the Keystone XL pipeline .

But with Liberal leader Justin Trudeau’s party predicted to win the most seats – if not an outright majority – experts say there is a chance of a thaw in relations between the two countries in time to facilitate real action on issues like climate change.

Of course, the US and Canada are deeply intertwined economically. Each is the other’s largest trading partner: trade between the two countries in 2012 – the most recent year for which data is available from the Office of the United States Trade Representative – totalled $707bn.

Canada is also the world’s largest national importer of US goods, spending $51bn a year on US-made cars alone. It is also the second-largest importer of US agricultural products.

After nearly 10 years in power, the Canadian Conservatives are a known quantity. But Harper’s relationships with other leaders on the continent – especially Barack Obama – have suffered. Trudeau’s centre-left Liberals, while also nominally pro-Keystone, have spoken out about the importance of balancing the environmental impacts of the policy. Tom Mulcair’s New Democrats have campaigned against it, echoing the opposition of US Democrats including Hillary Clinton .

Harper’s relationship with Obama also deteriorated when the Canadian prime minister felt pushed out of negotiations between the US and Japan over the Trans-Pacific Partnership , according to Professor Roland Paris , who studies international security and governance at the University of Ottawa.

There would be “much more alignment” between US Democrats and a Liberal Canadian government, said Elizabeth Roscoe , senior public affairs strategist at Hill and Knowlton, a Canadian public relations firm, especially as Trudeau and Clinton “share a lot of advisers, and approach”.

Republicans in the US “see more eye-to-eye” with the Conservatives in Canada, she said.

I think that what you would see very quickly with a Liberal government led by Justin Trudeau is a more conciliatory tone

Professor Roland Paris, University of Ottawa

Canadian participation in the US-led coalition against Islamic State militants in Syria and Iraq is also in question. Canada has six F-18 jets in Kuwait, flying sorties against Isis, and a special operations unit in Iraqi Kurdistan training Kurdish peshmerga forces. The Conservatives have campaigned to keep those missions going.

But the Liberals have indicated that they would end the air mission, and the NDP would remove all non-Nato Canadian military presence from the region.

Canada’s relations with Mexico have also suffered, in the face of Harper’s government’s hardline stance towards immigrants. The situation got so bad that Harper postponed a North American Summit scheduled for spring – the so-called “three amigos” summit.

“I think that what you would see very quickly with a Liberal government led by Justin Trudeau is first of all a change in tone, a more conciliatory tone,” said Professor Paris.

“I don’t think that you would get the hectoring [like you get with Harper], and that would be true both for relations with the US and Mexico.”

But perhaps the most important issue separating the two countries is the philosophical distance between Obama and Harper on the issue of climate change. Many US politicians, especially on the left, see Harper’s administration as having acted blindly in the face of environmental issues.

The issue is coming to a head: in April, the US took over the chair of the Arctic Council from Canadian environment minister Leona Aglukkaq. John Kerry, the US secretary of state, pledged to pivot the organisation’s focus towards the climate.

Related: Canada election: how Stephen Harper’s fossil fuel gamble may have backfired

Of the three leaders vying for electoral success in Canada, Trudeau is the only one to have addressed the Canada-US relationship directly in a speech.

“For our American cousins, the relationship is consequential. For us, it has often been definitional,” he said in June.

Trudeau accused the Conservatives of having “badly misread” the US-Canada relationship and said they had “missed important opportunities to cooperate with the US to find solutions to major issues like climate change”.

Trudeau is leading in the polls, so it seems increasingly likely that he will be the prime minister for the final year of Obama’s presidency and the opening years of his successor’s. It is possible the US president will find in him a more willing partner in his attempt to leave a lasting environmental legacy.

guardian.co.uk © Guardian News and Media 2015