EDMONTON, Alberta — Voters in Canada’s oil-rich Alberta province will decide Monday whether to begin a process that could lead to independence, testing national unity as U.S. President Donald Trump’s trade war and threats to make Canada the 51st state have rallied Canadians around their country.

Monday’s vote is not a direct referendum on independence. Alberta, home to most of Canada’s proven oil reserves — the fourth largest in the world — will decide whether to remain a province or begin the legal process toward a future referendum on separation.

More than 1.35 million Albertans, or 43% of eligible voters, cast advance or special ballots ahead of the referendum, far exceeding the 810,000 who voted early in the 2023 provincial election. Polls on Monday will be open from 9 a.m. until 8 p.m., with results on the independence question expected in the hours after voting closes.

But even if Albertans reject the proposal, separatist leaders say the movement that has transformed a fringe cause into a force in provincial politics is not going away.

Canadian Prime Minister Mark Carney urged Albertans not to take the outcome for granted and asked for a decisive result as he wrapped up two days of campaigning in his home province.

“Vote like Canada’s future depends on it because it does,” Carney told a pro-Canada rally Friday in Edmonton, where he grew up.

The vote also comes as Alberta reels from a deadly weekend fire at Canadian Forces Base Wainwright that killed four service members and injured 39 people, including 19 critically, during military training. Carney called it one of the worst peacetime tragedies for Canada’s military on domestic soil and ordered flags lowered to half-staff nationwide.

Alberta Premier Danielle Smith, who called the referendum despite opposing independence, recently cited a poll showing just 22% support for separation, a figure she said was still too high.

The biggest cheers Carney received at rallies in Calgary and Edmonton came when he spoke about diversifying Canada’s trade away from the United States. Crowds erupted in applause at both events, underscoring how Trump’s trade war and annexation threats have fueled Canadian nationalism even in traditionally conservative Alberta.

Carney has emerged as an unusually popular figure in conservative Alberta, where Liberal prime ministers have long faced resentment over federal energy policies.

Carney has taken a more energy-friendly approach, backing a proposed oil pipeline to the Pacific Coast and joining Smith in a show of unity against independence.

Carney warned that the referendum comes at the “worst possible time” and urged Albertans not to use their votes merely to send Ottawa a message.

Smith, who frequently clashed with Justin Trudeau, praised Carney for improving relations.

“I think what we can agree on is that we have had some real change in the last 18 months,” she said Friday.

Smith called a referendum she opposes, reflecting pressure from separatist activists within her governing United Conservative Party who helped bring her to power. Some of those activists helped oust former Premier Jason Kenney in 2022.

Kenney said separatism had traditionally been a fringe cause, with independence parties typically attracting only 1% or 2% of the vote. He said the pandemic mobilized activists angry over public health restrictions and government authority.

Separatist leader Jeff Rath said federal COVID-19 vaccine mandates drove him toward independence, while Tanya Clemens, co-chair of Let Alberta Decide, said pandemic restrictions spurred political organizing. Keith Wilson, the group’s other co-chair, was a lead lawyer for the 2022 trucker convoy that paralyzed downtown Ottawa for weeks in a protest against vaccine mandates and other COVID-19 restrictions.

Wilson argues that Alberta’s grievances go deeper. With much of Canada’s population concentrated in Ontario and Quebec, he said Liberal governments can win elections without significant support in Alberta, leaving the province vulnerable to federal policies opposed by its energy industry.

Wilson argues that Carney’s proposed Pacific Link pipeline illustrates the dysfunction, saying federal restrictions have discouraged private investment and could leave taxpayers financing the project.

Wilson rejects Alberta becoming an American state.

“I have no interest in substituting a master, that rules over my children’s future, who’s in Ottawa, with a new one who’s in Washington,” he said.

Other separatist leaders have sought contact with the Trump administration. Rath and fellow independence advocates met three times with U.S. State Department officials in Washington to discuss Alberta’s future.

Chief Sheldon Sunshine of Sturgeon Lake Cree Nation said Alberta cannot leave Canada without First Nations’ consent, citing treaties that predate the province. He said his nation would remain part of Canada even if Albertans voted for independence.

Sunshine condemned separatist leaders’ meetings with U.S. officials.

“It’s absolutely treasonous to the people of Canada, people of Alberta,” he said.

Wilson said the referendum campaign had generated unprecedented discussion about Alberta’s place in Canada.

“I think we’ve already hit success when you look at the voter turnout,” he said. “People are engaged and people are talking about this topic at a level that’s unprecedented historically.”

Rath said he would be thrilled if 30% of Albertans voted to begin the separation process, even without a majority. He wants Smith ousted as UCP leader and said the party could splinter, potentially creating a new pro-independence political party.

Some Albertans hope Monday’s vote ends the debate rather than beginning a prolonged independence struggle like Quebec’s.

Dave Malka, a 59-year-old Edmonton government worker attending a pro-Canada rally Sunday, criticized spending money on what he called a “referendum on a referendum” when the funds could have gone toward healthcare.

With Trump threatening Canada, Malka said, “It seems to be happening at the absolute worst time when we should be united, instead we’re fighting amongst ourselves.”

Malka expects a decisive rejection but fears separatists won’t give up. “This is only the start of separation Armageddon, if you will. This is their starting point,” he said.

Jake Graham, 35, of Calgary, attended Carney’s rallies wearing maple leaf pants and a Canada hockey jacket. He hopes a decisive vote settles the issue.

“I hope this squashes this for a long time to come and that it’s clear and decisive, that these grumblings disappear for a while and we can be a united Canada,” he said.