Unifor says it has presented a "comprehensive" proposal to General Motors Co. in a effort to settle a strike that began a week ago at the auto maker's Cami Automotive assembly plant in Ingersoll, Ont.

The proposal, made after meetings between the union and the company Saturday and Sunday, covered economic clauses of a new deal and the language in a new contract, Mike Van Boekel, chair of the Cami unit of Unifor local 88, which represents about 2,800 workers. They went on strike last Sunday evening.

"The ball is squarely in their court now," Mr. Van Boekel said.​

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The union had been seeking language in a new contract that would provide job security, designating the Cami operation as the lead plant for the Chevrolet Equinox crossover. Lead plant designation means it would be the first assembly plant to receive hundreds of millions of dollars in investment during the next redesign of the vehicle, effectively providing job security. But the union's proposal includes contract language that would ensure job security at Cami.

"The proposal addresses our outstanding items; such as job security, economics and contract language," the union said in a bulletin posted on its website.

Job security became the key issue after GM shifted production of the GMC Terrain to Mexico from Cami during the summer. The Terrain, also a crossover, shares the same platform or basic underbody as the Equinox.

The Equinox is also assembled at two GM plants in Mexico, but it is now the only vehicle made in the Ingersoll plant and is the largest source of one of GM's hottest-selling vehicles in the buoyant crossover vehicle market.

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Ripple effects from the strike are expected to spread to another GM plant in Canada on Monday when between 300 to 400 workers at the St. Catharines, Ont., transmission plant that supplies Cami are laid off. Industry observers also expect GM to idle some workers at the engine plant in Spring Hill, Tenn., that ships engines to Cami.

Several suppliers, including Magna International Inc., have stopped shipping parts to Cami and told workers at some of their operations to stay home.​