Negotiators explained to the union that the cost of continuing the month-long strike would mean losing more business to Mexico, which has already been filling Canadian production gaps since before the strike began.
The automaker is said to be considering a shift of production to Mexico if the walkout isn't called off.
Automotive giant General Motors has recently announced that it's increasing production of the Chevrolet Equinox model at two plants in Mexico.
The strike by Unifor workers at GM's plant in Ingersoll, Ontario, is in its fourth week and shows no signs of ending.
"This is a callous and heartless attitude for General Motors to take toward a community that has worked so hard to build its top-selling vehicles", Dias said in a Thursday Unifor news release.
Unifor is pushing for a commitment from GM that the Ontario plant will be the main producer of the hot-selling Equinox SUV.
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He said General Motors is taking advantage of the low pay scales for Mexican workers at the expense of higher-paid workers in the United States and Canada, as permitted by the North American Free Trade Agreement. Spokesmen for Unifor Local 88 declined to comment.
The CAMI plant is a prime example of a trend that has been happening for years, with GM adding plants in Mexico while closing Canadian and USA plants, Dias said.
"If Jerry is concerned about losing automotive jobs to Mexico, I think he's just adding to that situation by making it hard for General Motors to work with Unifor in Canada".
"This is the ugly side of NAFTA, that people don't want to talk about".
The talks have been shrouded in controversy due to US President Donald Trump's desire to keep jobs in the United States, and to ensure that all trade deals are fair for the three member countries.