The dispute has been festering for months. But the tension peaked when the pipeline’s owner, Kinder Morgan of Houston, said last weekend that it is suspending all nonessential spending on the program.
The company gave British Columbia until the end of May to end its attempts to delay or block the project. If not, the company said it would cancel its plan to add a second pipeline along aroute that opened in 1953.
To try to resolve the standoff, Mr. Trudeau has summoned Rachel Notley, the premier of Alberta, and John Horgan, her counterpart in British Columbia, to Ottawa for talks on Sunday.
Given the intransigence of both sides, even Mr. Trudeau’s top officials are downplaying the idea that the conversation will end the battle. But it may provide a glimpse of how Mr. Trudeau intends to grapple with an issue in which any resolution will inevitably alienate some voters, and on which there isn’t a clear national consensus.
“Canadians are quite divided,” said Shachi Kurl, the executive director of the Angus Reid Institute, a nonprofit polling firm based in Vancouver. “So much of this debate is rural versus urban Canada.”
Like the Keystone XL pipeline to the Gulf Coast of the United States, which was quashed by President Barack Obama and revived by Mr. Trump, the expansion of the existing Kinder Morgan pipeline is the latest attempt by the oil sands industry to push more of its product out to market. The pipelines have not expanded at the same rate as output from the oil sands, leaving many producers relying on expensive rail shipments to get their product to the United States, which currently buys almost all of Canada’s oil and gas exports.
Tankers filled by the current Kinder Morgan pipeline now sail to refineries on the West Coast of the United States. The extra capacity from an expansion could, in theory, allow oil sands companies to also begin shipping to Asian markets where demand for oil is growing, said Andrew Leach, an energy and environmental economist at the University of Alberta.
Ms. Notley, and her left-of-center New Democratic Party, surprised the Canadian political world in 2015 by bringing four and a half decades of Progressive Conservative rule to an end in Alberta. While she vowed in her campaign to take on the big oil interests in the province, politically she has no choice but to be a booster of the pipeline. Polls show that Albertans overwhelmingly want the expansion to go ahead.
To defend the expansion, the premier has shown a willingness to get tough with her provincial neighbor to the west. Earlier this year, Ms. Notley briefly banned imports of wine from British Columbia.
And unless the meeting Sunday changes her mind, Ms. Notley’s government is expected to introduce legislation next week that will give it the ability to restrict oil and gas shipments to British Columbia, and so driving up prices in the province.
“If the national interest is given over to the extremes on the left or the right, if the voices of the moderate majority of Canadians are forgotten, the reverberations of that will tear at the fabric of Confederation for many, many years to come,” Ms. Notley said on Monday, referring to the power-sharing system that Canada adopted in 1867.
This past week, Ms. Notley suggested that if Kinder Morgan decides not to go ahead with the expansion, the provincial government may buy and build the pipeline. Officials in Mr. Trudeau’s cabinet have suggested that the federal government might support such a plan.
For Mr. Horgan in British Columbia, the political calculus surrounding the pipeline expansion was more complex. The project is widely opposed in the areas around Vancouver and Victoria, the provincial capital, according to Ms. Kurl, the pollster. But support is strong for it elsewhere in the province, where resource industries are big employers.
Perhaps tipping the scale in his decision to try to block the project is that Mr. Horgan, also a member of the New Democratic Party, relies on the support of three Green Party members to pass legislation. That party, like many environmental groups, argues that Canada should not be building oil pipelines while it is attempting to reduce greenhouse gas emissions.
So Mr. Horgan plans to ask a court to determine if British Columbia can use local permits and provincial environmental laws to block the pipeline.
Mr. Trudeau’s government has cited several decisions, including some from the Supreme Court, that it contends give Ottawa complete authority over interprovincial pipelines. But it appears that the federal government can do nothing to stop Mr. Horgan from going to court. Any judicial review could at least delay the project.
The sparring between the two premiers may prove to be the least of Mr. Trudeau’s worries in the pipeline fight, as he tries to balance Canada’s economic dependence on the energy industry with his climate change commitments.
Environmental groups and some indigenous groups have vowed to stop the pipeline expansion through widespread civil disobedience. Those arrested already for breaking court orders to keep back from Kinder Morgan property include Elizabeth May, the leader of the federal Green Party.
Many environmental groups are using the pipeline expansion as a proxy in the fight against the oil sands, a source of fossil fuels that they condemn as excessively polluting.
“In an ideal world, we would like to see the federal government recognizing that it made an egregious mistake in approving this pipeline,” said Cam Fenton, a Canada strategy manager for 350.org, a nonprofit that opposes new fossil fuel projects. “At the end of the day polls change, science doesn’t. And it says we cannot deal with climate change and build pipelines.”