Canadian Prime Minister Justin Trudeau is an icon of progressive politics who has promised to “put a price on pollution.” Last week, to much applause, he proposed a ban on single-use plastics. On Monday night, his government declared a national “climate emergency.”

He is also now the public face of a Canadian plan to expand a pipeline that would triple the amount of crude oil that moves from the Alberta tar sands to the Pacific Coast for shipment around the world.

Such is his dilemma — and Canada’s.

Trudeau’s Liberal government announced Tuesday it will push ahead with the stalled Trans Mountain Pipeline expansion, $5.5 billion project that has long pitted the country’s energy sector against the concerns of environmental and some indigenous groups. 

Trudeau, announcing the decision at a news conference in Ottawa, pledged that every dollar earned from the pipeline will be used to fund projects to power Canada’s transition to clean energy.

“We need to create wealth today so we can invest in the future,” he said. “We need resources to invest in Canadians so they can take advantage of the opportunities generated by a rapidly changing economy, here at home and around the world.”

The move will be welcomed by the country’s struggling oil sector and the many Canadians whose fortunes are tied to it. Landlocked Alberta produces four-fifths of Canadian crude but struggles to get it abroad, and so must settle for selling at steep discounts against global benchmarks — hitting the province hard.

But many Canadians have protested the expansion proposal out of concern for oil spills and the continuing promotion of climate-changing fossil fuels. They question whether this is the moment to increase Canadian shipments of oil. 

Trudeau has been left to walk a tightrope between the two sides, taking heat from both as he limps toward a federal election this fall.

Janet Brown, an independent pollster and political analyst in Calgary, Alberta, said the prime minister’s challenge now will be positioning the decision as a safe path between Conservatives on the right and the New Democratic Party on the left.

“The message going forward will be: ‘The Conservatives don’t understand the environment, and the NDP don’t understand the economy,’ ” she said. “ ‘We, the Liberals, are the party that could do both.’ ”

Trudeau remains popular, but his government has been hit hard this year by questions about its handling of the prosecution of a construction company, SNC-Lavalin, from his home province of Quebec and the subsequent expulsion of two high-profile and popular cabinet members, Jody Wilson-Raybould — Canada’s first indigenous attorney general — and Jane Philpott, the former president of the Treasury Board.

The SNC-Lavalin scandal has exposed Trudeau to the toughest criticism of his short political career. Now his pipeline decision could make things worse.

Pipeline politics get at a very Canadian conundrum: How do you become a global leader on climate when your economy relies so heavily on the extraction of fossil fuels?

The Liberal government has long argued that to tackle climate change, Canada needs a strong energy sector, generating revenue today to fund the projects of tomorrow.

That has been a tough sell, at least when it comes to pipelines. Trudeau first gave the go-ahead for the Trans Mountain expansion in 2016. But the decision spurred legal challenges and protests, including a demonstration at which two members of Canada’s Parliament were arrested.

 Opposition was particularly fierce in British Columbia, at the end of the pipeline, where Premier John Horgan promised to block the project. Alberta, the oil powerhouse next door, responded by blocking wine imports from British Columbia and threatening to stop shipments of oil and gas to its neighbor.

Trudeau stepped in with an extraordinary plan: Buy the pipeline. His government announced last year it would spend $3.5 billion to take over the project. 

Canada’s finance minister, Bill Morneau, called the purchase “an investment in Canada’s future.” Alberta cheered the move. Others cast it as a sellout.

Still others wonder whether transporting oil to the Pacific coast is the best way to bolster the sector. Trudeau said Tuesday his goal was to decrease Canada’s reliance on the United States as a customer and increase shipments to new buyers, particularly in Asia.

“As we’ve seen over the past few years,” he said, “anything can happen with our neighbors to the south.”

But there is no guarantee business will be better elsewhere, and recent bad blood with China casts further doubt on the plans. Canada arrested Huawei executive Meng Wanzhou in Vancouver, B.C., in December at the behest of the United States; China has since charged two Canadians there with espionage and blocked some Canadian imports.

Tuesday’s announcement reignites the debate over the economy vs. the environment months before the October federal election.

A key question now is whether the approval means work can start or whether additional consultations could delay construction beyond the short Canadian summer.

Brown, the Alberta pollster, said she saw delays as a way to “rag the puck,” a hockey expression for running down the clock.

Alberta Premier Jason Kenney, a longtime Trudeau critic, expressed similar concern.

On Tuesday, he said he “appreciates” the re-approval but is anxious to see shovels in the ground.

“We need to get a fair price for our country’s energy to create good jobs & pay for public services,’ he wrote on Twitter. “Approval is not construction. So now let’s get it built!”

Others, of course, would welcome a delay. Wilson-Raybould, the former attorney general who clashed with Trudeau and now sits in Parliament as an independent, warned ahead of the announcement that re-approving the project would do little to resolve the conflict.

“It has been famously said that the definition of insanity is doing the same thing over and over again and expecting a different result,” she wrote ahead of the announcement. “I expect that is what we will see this week, as the government chooses to try to proceed, again, in a context of ongoing conflict and mistrust.”

Critics have vowed to fight the plan.

“A day after the Liberals declare a climate emergency, Trudeau approves the expansion of the Trans Mountain pipeline — a project directly threatening our environment,” tweeted Jagmeet Singh, the leader of the NDP. “It doesn't have to be this way. We'll continue to champion a plan that aggressively & honestly fights this crisis.”