The Canadian Auto Workers union has canceled a ratification vote for members at a General Motor Co assembly plant in Ingersoll, Ontario, originally scheduled for this Sunday, a union representative said.

The CAW, which represents just over 2,500 union members at CAMI Automotive Inc, have been bargaining for a new contract months ahead of the current deal's September expiration.

Mike Van Boekel, chairman of the CAMI plant unit of CAW's Local 88, said on Friday the two sides had yet to reach a deal and there are still issues of contention between the union and GM. He declined to provide further details.

The union had previously said it will seek the same core terms as in the contract negotiated in September 2012 for CAW members at other GM plants in Ontario.

A Globe and Mail report said one key issue involved about 350 temporary workers at the plant, which, under the 4-year master contract negotiated in the fall, resulted in making temporary workers permanent at its Oshawa, Ontario plant.

GM could not be immediately reached for comment.

Earlier this month, the Detroit automaker announced it was spending C$250 million ($244 million) to retrofit the CAMI plant for future vehicle production. The CAW expressed confidence at the time that the investment would result in more job security.

The CAMI plant, which operates 24 hours a day, six days a week, with mandatory overtime, is running at full capacity and produces the popular crossover utility models Chevrolet Equinox and the GMC Terrain.