CN workers backed a strike vote with negotiations set to resume on a contract for around 3,000 Canadian employees.
Unifor announced Sunday that workers with Local 100 are 98 per cent in favour of a strike while those with Council 4000 voted 97 per cent to back job action.
The union says the two sides are in the final stages of negotiations, with another round of talks set for next week.
Unifor says it broke off talks with CN last month and started the strike vote as it called on the railway company to withdraw concessions.
Unifor has said some concessions include loss of accrued vacation entitlements, removal of consent for early retirement at age 55, and a flex benefit plan that does not expand coverage and would make workers to pay for services such as dental.
CN says its latest offer includes a net increase in pay and benefits.
The Montreal-headquartered company says it does not expect its operations to be impacted if the workers — including clerical staff and mechanics — take labour action.