General Motors of Canada plans to halt production at one of its final two Oshawa assembly plants over the next year, a move that could eliminate thousands of jobs and hit Durham Region's fragile economy hard.

A GM spokesperson told BNN the automaker that teetered on the brink of bankruptcy a few years ago plans to remove the third shift at its Oshawa-based consolidated plant in the fourth quarter of 2012. A second shift will be cut in the first quarter of 2013.

The line will cease production altogether in June 2013, when the production schedule for the popular Chevrolet Impala ends.

There are currently 2,000 hourly employees working on the consolidated line.

"It is too early to predict accurately the job impacts related to these scheduling actions which will unfold over the next year as some employees may elect to retire and others will be on indefinite layoff," Adria MacKenzie, GM Canada's Corporate Communications Manager, said in an email to BNN.

Chris Buckley, president of Canadian Auto Workers union local 222, said he was frustrated by the company's refusal to provide clear answers about the closures and possible future products at the plant.

"To say that I am disappointed is an understatement. I am absolutely disgusted at General Motors' decision to close the consolidated plant," Buckley said during a heated press conference in Oshawa.

The line was originally scheduled to halt production in 2008, but saw its life extended due to strong demand for the Impala and the addition of the CAMI / Oshawa Equinox Shuttle Program.

"It's been a rumour that has been circulating for a while and today it has become a reality and it's a little bit devastating," said Oshawa mayor John Henry.

Both Henry and Buckley warned of the "ripple effect" in Oshawa and Durham which was largely built and grew as a result of the 75-year-old auto industry.

"Oshawa as of 2012 absolutely is more than a GM town … but when we continue to lose good paying jobs in my opinion you can't help but have a negative impact on the city of Oshawa," said Henry.

Buckley said the union would fight for the plant's survival during collective bargaining this summer. He urged the Ontario and federal governments to get involved in the fight, considering they invested $8 billion in industry bailouts.

"It's one thing for the company to survive," NDP MP Peggy Nash told reporters. "If the jobs don't survive here in Canada, it's not much good to Canadians."

Ontario Premier Dalton McGuinty said that while the closure was expected, it is "disappointing." He also suggested he'd be open to work with GM to find a way to extend the lifespan of the facility.

"It had been originally scheduled to close in 2008. We've been very grateful for the extension to this point in time," McGuinty said in Ottawa.

"If there's any way at all possible that we might work with GM to extend that even further obviously we'd be more than pleased to consider that."

GM's scaling back of its Canadian operations is part of a larger restructuring of its North American operations. The restructuring started two years ago under bankruptcy court protection.

That initial streamlining process led to the loss of tens of thousands of jobs in North America and the closing of several plants.

In Canada, GM has already closed a plant in Oshawa and a transmission factory in Windsor, Ont.

GM Canada currently employs more than 10,000 people. At their height, the automaker employed more than twice that number.