As a result, the country's largest railway could be headed to a strike or lockout as of mid-February following a 21-day cooling off period.
The Teamsters Canada Rail Conference says one of the sticking points is the company's demand to remove all rest provisions.
The union representing about 1,800 CN locomotive engineers says it is concerned the Montreal-based railway may be relying on government intervention and trying to "run the clock out" on talks.
Negotiations started last September ahead of the Jan. 1 expiry of the contract.
The railway said there is ample time to negotiation a new deal.
"Based on constructive discussions to date, CN is optimistic that the company and union will be able to reach a mutually satisfactory collective agreement without the threat labour disruption," spokesman Mark Hallman wrote in a email.
Note to readers: This a corrected story: A previous version said the union represents 1,700 locomotive engineers