The nation’s mail could have kept moving with the agreement if accepted by Canada Post officials.
However, the rejection means 50,000 workers could be locked out first thing Monday.
The tentative agreement brought forward by the the union representing Canadian postal workers suggested a 30-day “cooling-off” period accompanied by intense negotiations in an effort to avoid a lock-out or strike action.
Canada Post was in favour, but only on condition that the two parties go to binding arbitration if a deal is not worked in those 30 days.
The union balked at the suggestion fearing binding arbitration would mean giving up its right to negotiate a deal.
Both sides of the dispute are refusing to budge on key contract issues especially CUPW’s request for wage increases for rural mail carriers and the pension changes Canada Post says it needs to reduce costs.
Some postal workers have been without a contract since late 2015, while others have been without one since January 2016.