MONTREAL — The return of conservatives to power in oil-rich Alberta adds another province to a growing bloc of opposition to Prime Minister Justin Trudeau of Canada and his government.
Incomplete returns late Tuesday night showed the United Conservative Party led by Jason Kenney, a former Conservative federal cabinet minister, leading the New Democratic Party under Rachel Notley by a substantial margin.
While neither Mr. Trudeau nor his Liberal Party have ever been particularly popular in Alberta, the loss of a left-of-center ally is not welcome news for him six months before the federal election. Mr. Trudeau has been weakened by allegations from a former attorney general that he improperly intervened in a criminal case.
Much of Mr. Kenney’s campaign fed on economic and political frustration in the province, which has been afflicted by job losses in the energy industry since the global collapse of oil prices more than four years ago.
Throughout the campaign, Mr. Kenney said that his first priority if elected would be canceling Alberta’s carbon tax, defying a key element of Mr. Trudeau’s plan for mitigating climate change. But if he does so, the move will be largely symbolic, as the federal government has said it would swiftly impose its own carbon price on Alberta in response.
Mr. Kenney arrived for his victory speech in Calgary in the blue, full-size pickup truck — blue is his party’s color — that became a symbol of his campaign.
In his speech, Mr. Kenney blamed Mr. Trudeau’s government for exacerbating Alberta’s economic slump.
“We Canadians have been had,” he said to loud cheering. “In Ottawa we have a federal government that has made a bad situation much worse.”
Mr. Kenney called the five provinces, including Alberta, that oppose Mr. Trudeau’s national carbon pricing plan “the alliance of Canadian governments,” adding, “I look forward to deepening our work together.”
For Quebec, which is governed by conservatives who do not support building additional pipelines or killing carbon taxes, Mr. Kenney made a special plea in French and English. He suggested that unless it changed its position on pipelines, he would cancel tax transfers to Quebec from Alberta and other wealthier provinces, although those payments are guaranteed in Canada’s Constitution.
As he did during the campaign, Mr. Kenney slammed environmental groups, particularly those opposed to pipelines. Referring to them as “foreign-funded special interests,” Mr. Kenney accused them of carrying out “a campaign of economic sabotage against the province.”
He promised to investigate the funding of environmentalists, saying, “The days of pushing Albertans around with impunity just ended.”
Mr. Kenney made no mention of Mr. Trudeau’s decision to buy a pipeline to the Pacific Coast after its American owners began backing away from plans to expand its capacity. But he charged that a lack of pipeline capacity meant Alberta was selling its oil “at fire sale prices,” adding that “we are subsidizing, in the process, the U.S. economy.”
Four years ago, Ms. Notley, whose New Democrats are the furthest to the left of Canada’s mainstream parties, surprised much of the country by ending 44 years of conservative rule in Alberta. Ms. Notley, who will remain the official opposition leader, was Canada’s only female head of a provincial government.
In a statement, Mr. Trudeau said he would work with Mr. Kenney on “taking decisive action on climate change while getting our natural resources to market.”