Unifor says it is still facing resistance from General Motors as an Oct. 9 deadline approaches for contract negotiations with the automaker.
National president Lana Payne says some progress has been made, but that there's nothing automatic about having the company agree to the terms it reached in September with Ford Motor Co.
The union will also have to work to convince its own members.
Union members at Ford only voted 54 per cent in favour of their deal, and it was voted down by skilled trade members in Windsor and Oakville.
Larry Savage, chair of the labour studies department at Brock University, says members at GM will likely vote in favour because there's much to gain for the many new hires there.
Stellantis members, however, will be much tougher, as Local 444 president Dave Cassidy reportedly says he plans to push for better terms and break the pattern set by Unifor's deal with Ford.