At a rally near the plant last summer, Trump talked about passing by big factories whose jobs "have left OH", then told people not to sell their homes because the jobs are "coming back".
GM said it will double the resources it allocates to electric and autonomous vehicles in the next two years, integrate vehicle and propulsion engineering teams and "compress" global product development campuses.
The Oshawa plant is one of five in North America that the automaker plans to shut down as it restructures to cut costs and focus more on autonomous and electric vehicles. The union that represents its Canadian workers said in a statement that GM's expected decision does not "live up to the spirit" of certain commitments the company made to union members during 2016 contract negotiations.
According to GM, the Oshawa plant employed 2600 hourly employees and 300 on salary.
Canadian Prime Minister Justin Trudeau said he spoke to Barra on Sunday to express his "deep disappointment" with the closure. GM says it will allocate future products to fewer plants next year amid "changing customer preferences in the USA and in response to market-related volume declines in cars".
GM said it plans to cut its salaried workforce by 15 percent.
Trump says he's being very tough on GM chief executive officer Mary Barra.
GM's latest move includes the possible closure of seven plants worldwide, as the firm shifts its focuses from away from a stagnant sedan/saloon auto market.
"The first thing I said to (the president of GM) 'is there anything we can do as a province, absolutely anything, ' and the answer was no, there's nothing".
Additionally, GM plans to cut two drivetrain facilities: Baltimore Operations in Maryland and the Warren Transmission plant in MI. The automaker intends to close the plant in December, 2019.
GM says assembly plants in Detroit, Warren, Ohio and Oshawa, Ontario, Canada will be shuttered in 2019, along with propulsion plants near Baltimore, Maryland and Warren, Michigan.
The US$6-billion in savings includes cost reductions of US$4.5 billion and lower capital expenditure annually of nearly US$1.5 billion, GM said.
Propulsion plants in Maryland and MI also will not be given any product. GM expects to spend $1 billion on Cruise this year to build the next generation of cars. "There is a long-standing, proud history in terms of General Motors's presence in Oshawa, so now to see this plant close.is incredibly devastating".
"It's not just General Motors, it's all the parts suppliers, logistics companies, they're all involved in putting these vehicles together and if we're gone it's a lot bigger than just GM", said Jesse Forbes, who's worked for GM in Oshawa for 17 years.
The company has said tariffs on imported steel, imposed earlier this year by the Trump administration, have cost it $1bn.
Meanwhile, GM's plant in Oshawa, Ontario, will stop making the Impala, Cadillac XTS and 2018 full-size pickups in the fourth quarter of next year.
Wolikow said he's got three kids, and that he and his fiancee, who works at a Cracker Barrel, are racking up credit card debt just to pay for basic living expenses. "The ship has already left the dock", he said.
The union, he said, "does not accept the closure of the plant as a foregone conclusion" and "will vigorously fight again to maintain these good-paying auto jobs".
Bobbi Marsh, who has worked assembling the Chevrolet Cruze compact auto at the OH plant since 2008, said she can't understand why the factory might close given the strong economy.