Prime Minister Justin Trudeau is urging Canada’s two largest railways and unionised workers to reach a deal to avert a strike that businesses warn will cause significant harm to the Canadian and US economies.

Canadian National Railway and Canadian Pacific Kansas City plan to lock out more than 9,000 workers from the Teamsters Canada Rail Conference just after midnight. The union issued a strike notice to Canadian Pacific for the same time. Trudeau said Labor Minister Steven MacKinnon is meeting with the parties in Calgary following a Tuesday meeting in Montreal.

“My message has been straightforward: It is in the best interest of both sides to continue doing the hard work at the table to find a negotiated resolution,” Trudeau told reporters Wednesday in Buckingham, Quebec. “Millions of Canadians — workers, farmers, businesses — right across the country are counting on both sides to do the work and get to a resolution.”

MacKinnon declined a request from Canadian National to impose binding arbitration last week, but it remains an option as the hours tick down to the midnight deadline.

The strike would be the first in nearly six decades involving both railway companies, which account for 80% of the Canadian rail network. Business groups have said C$1-billion in goods are transported by rail each day in Canada. A rail stoppage would also thwart some commuters in Toronto, Montreal and Vancouver.

The dispute has already begun to impact the movement of products including wheat, chemicals and fertilizers throughout Canada and the US. The two rail operators started a phased shutdown of the network last week and AP Moller-Maersk has said it’s no longer accepting shipments for Canada that need to travel by train.

Multiple industry and business associations, including the US Chamber of Commerce and its Canadian counterpart, have urged Trudeau’s government to step in to stop a “devastating” rail stoppage from happening. US Transportation Secretary Pete Buttigieg has said his department is closely monitoring the negotiations, engaging with Canadian officials and tracking the flow of vital goods to US consumers and businesses.

The union is seeking stronger provisions around rest time, while the companies say their offers meet regulatory requirements and in no way endanger safety.

Deputy Prime Minister Chrystia Freeland also urged the companies and union to swiftly resolve their dispute, telling reporters in Edmonton that she has “no patience with dilly dallying” given the “serious” consequences. Freeland, who’s also finance minister, declined to comment on what it would take for the federal government to intervene, adding that she thinks the best deals are reached at the bargaining table.

“I want them to roll up their sleeves to recognize Canadians need them to get this done, to reach a deal so we can keep on moving forward,” she said.