The Canadian Union of Postal Workers (CUPW) has rejected the latest contract offer from Canada Post, meaning that postal workers will continue to strike as the busy holiday season looms nearer.

“It doesn’t address our core issues,” CUPW national president Mike Palecek told CTV News Channel on Saturday. “We have issues of health and safety, of equality that have to be settled -- and our members gave us a very strong mandate to settle these issues.”

The offer was rejected well before a midnight deadline, with Palecek saying that it was not even worth putting to a union-wide vote.

“Artificial deadlines are not going to help us settle a negotiated collective agreement,” Palecek said.

That means that the rotating strikes that began Oct. 22 will continue into the foreseeable future.

“We’re frustrated too,” Palecek said. “And in fact, we shouldn’t have to be here. Canada Post has been discussing these issues with us for years and they’ve refused to move on any of them.”

The dispute is creating uncertainty during one of the busiest times of year for the corporation -- and for Canadian shoppers. At least 600 Canada Post trailers are currently sitting idle with more than 1.5 million pieces of undelivered mail.

Without a settlement, that backlog is expected to grow.

“At our processing facility in Mississauga, which is our largest in the country, we’re looking at a backlog of over 400 trailers,” Canada Post spokesperson Jon Hamilton added. “That’s trailers full of, at least (in) each one, 2,500 parcels and packets waiting to be processed and then delivered.”

That backlog has become so bad that Canada Post has even urged international partners to halt mail shipments to Canada -- an action that may force some Canadian business owners to explore other options.

Cory Krul is the owner of Cornelia Bean, a coffee and tea retail boutique in Winnipeg.

“If we need to take other means, then we’d do Canpar or UPS or some other way of getting product to our customers,” Krul said.

For others like Karen Pickles, who sells gift boxes online through her company Stresscase, it all might be too much.

“We’re heading into the Christmas spike right now,” Pickles said from a Calgary post office. “So hopefully the strike isn’t going to interrupt our business because it would kill us.”

Federal Labour Minister Patty Hajdu has been in contact with both sides in the dispute and is urging them to come to a resolution.

Meanwhile, the Liberal government has been vague about what kind of action it is considering, with Prime Minister Justin Trudeau only saying that “all options will be on the table.”

“We have a government that says they believe in collective bargaining,” Palecek of CUPW said. “We hope their patience would match those principles.”

With a report from CTV’s Annie Bergeron-Oliver in Ottawa