MIRROR, Alberta—Prime Minister Mark Carney wants to use a Group of Seven summit starting Sunday to showcase Canadian strength and unity. But global leaders will be visiting an oil-rich province that is considering a divorce from Canada.

Rising disaffection in Alberta presents a challenge for Carney, who was governor of the Bank of England when U.K. voters decided to leave the European Union in the 2016 Brexit referendum. Carney has promised since winning election in April to strengthen Canada’s economy and reduce dependence on the U.S.

The feat would be impossible without Alberta, which holds almost all of Canada’s crude-oil reserves—the world’s fourth largest. The Western province helps drive Canada’s economy. Alberta contributed almost as much to Canada’s growth last year as its financial and manufacturing hub of Ontario, which has more than three times the population, government figures show.

Many Albertans feel unappreciated by political leaders in Ottawa, who, in a decade of Liberal Party rule, have focused on reducing greenhouse-gas emissions and threatening to curb an oil-and-gas sector that generates about a quarter of the province’s gross domestic product.

Nearly half of Albertans support independence, a survey last month by the polling firm Leger found. Another by the polling firm Angus Reid found that more than a third of 800 Albertans supported separation and that more than a fifth would support joining the U.S.

“There is a large and growing number of Albertans that have lost hope in Alberta having a free and prosperous future as a part of Canada,” Premier Danielle Smith of Alberta said recently. “They are quite literally our friends and neighbors who have just had enough of having their livelihoods and prosperity attacked by a hostile federal government.”

Smith, who said she doesn’t support separation, is making it easier for citizens to initiate a referendum on Alberta’s future within Canada. Her party has passed a bill that would reduce the number of signatures that citizens groups need to trigger a provincewide referendum. Alberta gives citizens 120 days to collect the 177,000 signatures they need once the bill goes into effect July 1.

A demand for a provincial referendum, at the Whistle Stop Cafe.

Among the groups poised to solicit petitioners is the 250,000-member Alberta Prosperity Project. It was co-founded by the constitutional lawyer Jeff Rath, a former national rodeo champion who owns a horse ranch southwest of Calgary. He said he began to support independence because he thought pandemic restrictions under then-Prime Minister Justin Trudeau were hurting Alberta’s interests.

Rath said that Alberta gives much more to Ottawa than it gets back and that the province would be better off economically if it used the funds for itself. “There’s nothing Canada can offer us that’s more valuable than a complete cessation of federal taxation and regulation in Alberta,” Rath said.

Alberta contributed $180 billion more to the federal government than it received between 2007 and 2022, according to the conservative Fraser Institute. Under Canada’s federal system, wealthier provinces pay other regions to spread the country’s wealth. Quebec received $9.5 billion in transfers to help pad its budget last year. Quebec has resisted attempts to build a pipeline from Alberta’s landlocked oil sands to Canada’s eastern coast, infuriating Alberta’s leaders.

Jeff Rath, owner of a horse ranch southwest of Calgary, says pandemic restrictions were bad for Alberta.

A poster in the home of Rath with referendum language.

Since Carney succeeded Trudeau as prime minister, Carney has tried to placate Albertans’ concerns. He has promised to turn Canada into an “energy superpower” using oil, gas and renewable energy. He has introduced legislation that would make it easier to approve infrastructure such as oil pipelines deemed to be of national interest.

Smith said Carney had a small window to show he can get energy projects approved.

“There has to be a real demonstration, and very soon, that some of the priorities of Alberta are going to be addressed,” she said in an interview.

Jason Kenney, a former Alberta premier and secession opponent, said a referendum would tear at the province’s and the country’s social fabric. He said Carney would strengthen the independence movement if he doesn’t make good on building more pipelines.

“We’re all filled with hope, but ready to be disappointed,” Kenney said.

David Parker says he doesn’t think Canada can be fixed.

David Parker, a political organizer and independence supporter, said federalists in Alberta could be surprised in a vote, just as so-called remainers were in the U.K.

“Central Canadians don’t understand the anger here because they don’t think about us at all,” he said. “I don’t think Canada can be fixed at this point.”

Chris Scott owns the Whistle Stop Cafe in the hamlet of Mirror, population 480, which became a flashpoint for pandemic policies after Scott refused to abide by distancing and masking restrictions. Police closed the diner for seven weeks.

A customer at the Whistle Stop Cafe and the owner, Chris Scott.

Support for provincial independence at the Whistle Stop Cafe.

Today, blue Alberta provincial flags fly on the property, and the front door is decorated with a sticker that declares, “Alberta First, Alberta Free.”

Scott, who worked in the Alberta oil patch for 20 years, said he doesn’t want to help make Easterners rich off the province’s wealth. “They’ve been milking the West,” he said.

Carney’s election win in April, which upended earlier expectations for a Conservative Party victory, only confirmed for him and others that the rest of Canada wasn’t attuned to Western concerns.

“There are a lot of closet separatists,” he said. “It’s not a whisper in the wind anymore.”