TORONTO - Canada's Unifor autoworkers' union said on Tuesday its first strike target in contract negotiations would be General Motors Co, and set a strike deadline of midnight on Sept. 19.

Under a strategy called pattern bargaining, the union typically selects one company for intensive negotiations. That company's deal sets a pattern, and other auto manufacturers are expected to agree to very similar contracts.

"I don't think there's going to be a strike," said Unifor National President Jerry Dias. "I think General Motors is going to work with us to find a solution."

But he added that the carmaker will have to shift its strategy and announce its investment plans for Canada before any deal is ratified.

Bargaining with General Motors Co, Ford Motor Co and Fiat Chrysler Automobiles kicked off earlier this month, but will move into high gear as union officials narrow their focus to GM.

Four-year contracts covering about 3,900 workers at GM, 9,750 at Fiat Chrysler and 6,700 at Ford expire Sept. 19.

While negotiations often run up to or past strike deadlines, Unifor, formerly the Canadian Auto Workers, does not strike often. The union's last strike against the automakers was in 1996, when members walked off the job at GM.

Union leaders have said winning new investments is their top priority in the talks, highlighting GM's Oshawa assembly facility, Fiat Chrysler's Brampton assembly plant and Ford's Windsor engine plant as being of particular concern.

Pay and benefits will also be on the table. During the last round of talks, the union accepted a 10-year period before new hires reach regular pay rates and a hybrid pension plan that left new workers with less-generous benefits, with only a portion of their retirement payments guaranteed.

A strike at GM would shut down production of the Chevrolet Impala, Buick Regal and Cadillac XTS at the Oshawa assembly facility. But the Impala is also built at the Hamtramck assembly plant in Detroit, and the Buick Regal and Cadillac XTS are not especially strong sellers.

The CAMI assembly plant in Ingersoll, Ontario, which builds the popular Chevrolet Equinox crossover and the GMC Terrain SUV, has a separate labor contract, so a strike would not affect it directly. But GM's St. Catharines powertrain plant, which is under the main contract, supplies CAMI.