Rotating postal strikes are threatening the Black Friday shopping rush in Canada, with the government resisting calls from retailers to end a dispute that has undelivered parcels piling up.

Unionized workers rejected a Canada Post’s “last ditch” offer Monday calling for a temporary return to work through the holiday season. Labor Minister Patty Hajdu said the solution is to “get back to the table” and negotiate a new contract. Prime Minister Justin Trudeau echoed that Tuesday, telling reporters Canadians need regular mail service back and that his government is still studying its options, which include a back-to-work order.

The holiday season is about to go into full swing, with many Canadian stores adopting Black Friday sales that are common south of the border. Electronics and appliances sales surged nearly 13 percent last November from a year earlier because of the promotions, according to Statistics Canada’s initial estimates. Questions about shipping delays this year could weaken confidence in online purchases and hurt merchants that rely on e-commerce.

The Retail Council of Canada sent an open letter to Trudeau on the weekend saying the government must end the strike. The group says the situation is heading into crisis territory because the pace of parcel traffic is about to double in an already strained postal system.

“This ship can be righted, but it’s getting down to a matter of a few days,” Karl Littler, the council’s vice president of public affairs, said by phone Monday. “A clogged system isn’t going to be able to deal with that ramp-up.”

Deepening Backlog

Rotating strikes over the past month have already left hundreds of truck trailers full of unprocessed mail at Canada Post depots in Toronto and Vancouver. The government-owned corporation delivered a record 62 million parcels over the 2017 holiday season, including a single-day record 1.8 million shipments on Dec. 4, according to its annual report.

The Canadian Federation of Independent Business is also sounding the alarm. “Most members don’t really care how Canada Post goes back to work, they just want them to go back to work,” Vice President Monique Moreau said Monday. Costs so far have run into the thousands of dollars for typical small businesses, including late payments and owners making deliveries themselves, she said.

Some merchants are already finding alternatives. Etsy Inc.’s Canadian website posted a message saying orders won’t be delayed and will be sent by United Parcel Service if necessary. Amazon.com Inc.’s Canadian page says it uses the postal service and other couriers such as UPS DHL Worldwide Express.

Etsy sent Trudeau a letter Monday asking for legislation to end the labor dispute. “As Black Friday and Cyber Monday approach, it is essential for Etsy sellers in Canada to have their shops open and ready for business, and that they be able to deliver on customer expectations of fast and reliable shipping,” Erin Green, regional director for North America, wrote.

Amazon Canada didn’t immediately respond to a request for comment on the labor dispute.

Domestic sales on EBay Canada will probably hold up through this weekend because customers are expecting slower delivery, but could suffer toward Christmas when more people ship gifts to friends and family, according to General Manager Andrea Stairs. “There are real Canadian businesses that are caught in the crossfire,” she said by phone Tuesday. “At this point, back to work legislation is exactly what is called for.”

Canada Post offered a 2 percent pay raise and a four-year contract last week. The Canadian Union of Postal Workers made a counteroffer seeking a 2.9 percent annual wage increase including protection against inflation. The postal service told commercial customers late Monday it can no longer honor its usual delivery standards.

Any decision on a back-to-work order rests with Trudeau and his cabinet. “I’m very preoccupied with the fact that Christmas is coming,” the prime minister told reporters Tuesday. “Important shopping days are coming and we need to see a resolution. All options are on the table.”