TORONTO -- Unifor says it has suspended a media campaign against General Motors amid productive talks with the automaker on the future of the company's assembly plant in Oshawa, Ont.

The union says the company has been clear it won't extend vehicle manufacturing at the Oshawa plant beyond the end of the year, but that there is potential to transform operations to maintain some jobs.

Union president Jerry Dias, who sat down Tuesday with senior GM officials in Detroit, said a deal could be reached within weeks while declining to offer details.

"It's about maintaining a footprint, and it's about being in a position to build for the future. So I'm feeling more optimistic now than I have in a long time."

He said it's still unclear how the talks will end up, but that the plan is about more than maintaining empty buildings.

"We're having very aggressive conversations with General Motors about a short-term fix and a long-term plan."

The union said that in light of the positive talks that started Feb. 25, it had suspended its media campaign against the company. The union ran numerous ads, including a Super Bowl television spot in Canada, criticizing the company's lack of loyalty to Canadian workers and encouraging consumers to boycott GM vehicles built in Mexico.

It says the two sides have agreed to continue talks over the coming weeks.

GM announced last November that it would end production at the Oshawa plant by the end of 2019, set to affect about 2,600 union workers at the assembly plant, as part of a wider restructuring that would also see four U.S. plants close.

The company has come under significant criticism for the move. U.S. President Donald Trump called GM out in a tweet Monday demanding that it keep open its plant in Lordstown, Ohio and close a plant in Mexico or China instead.

Dias said that Prime Minister Justin Trudeau's discussions with GM CEO Mary Barra, including a call Trudeau tweeted about Monday, have helped in discussions.

"I think that his involvement helped in a significant way."

GM has noted that many workers at its Oshawa plant qualify for retirement, and it has committed to helping workers with job placements and retraining.

The company said Tuesday it continues to have discussions with Unifor "with regard to supporting our people in Oshawa."