TORONTO -- With one week left before the Canadian Union of Postal Workers' strike mandate expires, a spokesman for the union says negotiating with Canada Post without the mandate is not an option.

Both sides say little progress has been made on major contract negotiation issues as the country's largest postal union nears the end of their 60-day mandate.

CUPW national president Mike Palecek said Thursday that the union needs the mandate, which allows them to call for a strike, to keep them on equal footing through the talks.

Rather than ask the union membership for another strike vote, Palecek said one option is a freeze on the negotiation timeline, which would require mutual agreement from both sides.

But in a statement released Wednesday, Canada Post said prolonging the strike mandate would create further uncertainty for Canada Post customers and called CUPW's requests for their support to extend the strike mandate "unprecedented" and "completely inappropriate."

The statement says Canadians "could expect" a strike notice to be issued between now and the Aug. 25 strike mandate expiry.

Both sides said they are willing to negotiate and blame each other for the stalled talks.

CUPW, which represents 50,000 Canada Post workers, previously held a strike vote for the current mandate, but Palecek said they would prefer to look at other options to extend it.

The union is concerned that without a strike mandate, they won't be able to respond to changes Canada Post could make to their working conditions.

"We will not leave our members in a position where a strike mandate is not in place," Palecek said.

"We've been clear about that precisely because the level of trust between the two parties is very low right now."

Palecek said CUPW has not yet asked Canada Post to freeze the negotiation timeline, but the union will "discuss possibilities" after they have those conversations.

Canada Post spokesman Jon Hamilton said the strike mandate is creating uncertainty for businesses and customers, and barring a membership vote in favour of another mandate, the union should let it lapse.

"One option is they let it expire and do nothing, and if you don't want to strike, why would you need a strike mandate? Strike mandate or no, we want to negotiate," he said.

"We should be talking and getting to the end of this."

Hamilton added CUPW's demands would be too costly for Canada Post to bear.

"Right now we're at an impasse and it's having an impact on our business, and that's not good," he said.

In July, Canada Post proposed binding arbitration to reach an agreement, which the union rejected. An arbitrator recently accepted Canada Post's proposal for a new collective agreement for rural postal service employees.

Palecek said the union won't accept binding arbitration because they're committed to finding an agreement through collective bargaining.