The union's contract with the Detroit Three automakers - GM, Ford and Chrysler - expires Monday night, and the union has set its sights on GM as it tries to secure more production at the automaker's plant in Oshawa, Ont.
Unifor National President Jerry Dias has said they will not extend Monday's strike deadline. Williams said he has a lot of respect for Dias.
The Buick Regal, Cadillac XTS and Chevrolet Impala passenger cars made on the other assembly line are scheduled to go out of production by 2019 and no replacement vehicles have been allocated.
Dias said the union has not yet received a contract proposal from GM, but he remains confident the automaker will eventually offer a product.
Asked whether the two sides were discussing a new product for GM's Oshawa assembly, Dias said: "They understand that they have to do something, but we're not really talking about anything specific, which is problematic".
One of the region's biggest auto parts suppliers fears it will be forced to lay off workers if General Motors and Unifor fail to reach a tentative contract agreement ahead of a strike deadline of midnight Monday.
GM Canada is focused on working with Unifor to reach a "mutually beneficial and competitive new agreement", spokeswoman Jennifer Wright said in an email.
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There are no obvious products that would go into the Oshawa plant, and the automaker has said it would only make future product decisions after a labor deal.
That's when a contract was signed, and then soon after, "even before the ink was dry", as national president Jerry Dias puts it, GM shut down the truck assembly plant in Oshawa and moved Camaro production to MI.
A strike would send 3,860 GM hourly workers from GM's Oshawa plant, its St. Catharines transmission and engine plant and a parts distribution center in Woodstock to the picket lines, which analysts say eventually could hamper production at GM's US plants. In negotiations with GM there are 4,000 Unifor members in Oshawa, St. Catharines and Woodstock.
At stake is the future of the Oshawa plant, with about 2,500 direct jobs and thousands more at supplies throughout Ontario's manufacturing heartland. The union has extended its contracts with the two companies, meaning workers would not be in a legal position to strike on Tuesday.
The Ingersoll plant, which is running three shifts, makes the Equinox and GMC Terrain vehicles.
The impact of a strike on GM's North American production is uncertain because the automaker has capacity outside Canada to build the same truck engines and transmissions produced at its St Catharines plant.
Canada has been struggling to get new investment from automakers in its once-thriving auto industry, losing out to the Southern United States and lower-cost Mexico.