Conservatives in western Canada have won a critical regional election, with voters rejecting the province of Alberta’s incumbent leftwing government and setting the stage for a fight with the federal government over environmental policy.

The bitter election was fought largely over the economy, pipelines and the environment. Running on a campaign slogan of “Alberta: Strong and Free”, winner Jason Kenney and his right-wing United Conservative party (UCP) pledged to revive the province’s troubled oil and gas sector, cut taxes and scale back environmental policies enacted by the previous government.

“Alberta is open for business,” Kenney told a raucous crowd, after pulling up to the stage of his victory celebration in his blue campaign pickup truck. “Help is on the way and hope is on the horizon.”

Premier Rachel Notley of the leftwing New Democratic party was vying for her second mandate in the province of Alberta, having previously shocked the country when she and her party stormed to victory in 2015. The historic win broke an unprecedented 44 years of conservative rule in the province and was heralded as a new age in Alberta politics.

But a second time around, her promises of a balance between environmental regulation and businesses growth appears to have been rejected by a majority of Albertans, with frustrated residents defecting to the the UCP. Despite her strong favourability ratings, Notley becomes the first premier in the province’s history to fail to secure a second term.

She was the last remaining female premier in the country, a dramatic shift from 2013, when six women held the job in five provinces and one territory. “I am enormously proud of our record – and you should be too,” she told supporters as she conceded the race to Kenney – adding that she would remain as opposition leader. “I wish him and his government well. We all do and we must because we all love Alberta.”

With Kenney’s legislative majority, the province appears set to return to the status quo of conservative government.

Loud cheers broke out in the Big Four Roadhouse, a venue in the Calgary Stampede grounds where UCP members had gathered. Provisional results at 11pm eastern (0400 GMT Wednesday), an hour after voting ended, showed the party had won 62 of the 87 seats in the provincial legislature.

“This means vindication of the very, very difficult defeat that we received in 2015. That was a protest vote, this is a positive vote,” said Marguerite Denis, who co-managed the campaign of one UCP candidate.

Much of the bitter campaign centred around pipelines, with both Notley and Kenney vowing to complete the Trans Mountain pipeline, a critical infrastructure project for the province that has languished in regulatory review since the summer. A prolonged energy crisis in the province – largely the result of overproduction of oil with no clear access to market – has forced energy companies to sell crude at deep discounts, costing thousands of jobs and billions in lost government tax revenues.

While the majority of voters expressed frustration over the economic crisis in the province, they remained skeptical of the socially conservative positions taken by the UCP. Throughout the election Kenney’s party was dogged by accusations of racism and homophobia, promoting candidate resignations and statements of contrition from others.

United Conservative leader Jason Kenney Photograph: Candace Elliott/Reuters

Premier-designate Kenney will have to deliver on promises he made to revitalise the region’s oil sands, something experts caution might be more difficult than anticipated given the high cost of production and a wariness of investing in capital-intensive projects.

His victory is the latest in a string of conservative wins at the provincial level since 2015 and spells trouble at the national level for Justin Trudeau and his Liberal government, which has recently fallen in the polls after a political scandal and is locked in multiple legal battles with provinces over the federal carbon tax.

Kenney has vowed to scale back the key aspects of the province’s environmental legislation. But any changes to environmental policy that fall below Trudeau’s emissions threshold will trigger the federal government imposition of a carbon tax on the province.