MONTREAL -- As Canada gets set to reopen the border to vaccinated Americans, a border guard strike could begin Friday morning. If this happens, Montreal businesses could feel the sting.

The U.S.-Canada border has been shut down to non-essential travel for 17 months, but border security agents have been without a contract for twice as long and, unless there is a last minute agreement, they could begin work-to-rule tactics Friday at 6 a.m.

It's something that's preoccupying Prime Minister Justin Trudeau.

"Our border guards have had an extremely challenging role to fill in the past year and a half, and I want to thank them for their work and tell them we will we work with them to resolve these challenges," said Trudeau.

Problems at the border could spell problems for Canadian businesses trying to navigate the fragile post-pandemic recovery.

"Small businesses are still struggling, only 35 per cent of them are making normal sales, and obviously a strike will have an impact," said vice president of national affairs at the Federation of Independent Businesses Jasmin Guenette.

The border agents' union said it is seeking higher pay and broader rights for all its agents to carry firearms.

It also wants to address what it calls a toxic workplace.

“We truly hoped we wouldn’t be forced to take strike action, but we’ve exhausted every other avenue to reach a fair contract with the government,” the union said in a statement.

With the land border set to re-open next Monday, the union said travellers, including tourists and businesspeople from the U.S. could expect significant delays.

“Ninety per cent of frontline Border Services Officers have been identified as essential, meaning that they will continue to offer essential services if there is a strike," the CBSA said. "We expect that our officers will continue to fulfill their duties with the highest level of integrity and professionalism.”

The CFIB said the recent strikes at the Port of Montreal proved how costly border delays can be for Canadian businesses and they can't afford another dispute.

"It will have an impact on economic recovery, it will have an impact on small business recovery and businesses across the country cannot afford a strike at the border," said Guenette.

Last-minute negotiations are planned, but the countdown to 6 a.m. is on.