The national president of Unifor, the union representing Chrysler workers in Ontario, has rejected the idea of opening up contracts in an effort to get Chrysler to invest in its two plants in the province.

Chrysler CEO Sergio Marchionne said the company plans on investing more than $1 billion in its minivan platform but would not guarantee it would be made in Windsor.

At the North American International Auto Show on Monday, Marchionne suggested public money and union concessions will be needed for the next minivan to be built in Ontario.   

Jerry Dias head of Unifor said the union will "absolutely not" open its contracts with Chrysler but agreed that using public money is a good idea.

"Smart governments invest in the auto industry," Dias said. "The reality is is that that the provincial government [and] the federal government have put some money in Ford, they've put some money in the auto industry.  It's not uncommon for [Marchionne] to make that request."

More than 4,000 people work at the Chrysler Windsor Assembly Plant. More than 3,000 work at a plant in Brampton.

Dias said he has not yet been contacted by Chrysler about the potential investment.

"It's concerning that he wouldn't lift the phone, there's no question about it," Dias said. "But Sergio is a different individual. So, I'm not surprised but I would have appreciated the phone call."

Although he wouldn't commit to Windsor getting the investment, Marchionne praised the Windsor Assembly Plant for having "one of the best work forces around."