DETROIT — Shifting demand from cars to trucks and SUVS is forcing General Motors to lay off more than 2,000 workers indefinitely at two assembly plants in Ohio and Michigan starting in January.

The company said Wednesday it will suspend the third shifts at factories in Lordstown, Ohio, and in Lansing, Michigan, because of the market change, which is growing and shows no sign of abating.

About 1,250 workers will be furloughed at the Lordstown plant, which makes the Chevrolet Cruze compact car, starting Jan. 23. Another 840 will be idled at the Lansing Grand River factory, which makes the Chevrolet Camaro muscle car and the Cadillac ATS and CTS luxury cars, when their shifts end Jan. 16.

“It’s supply and demand, and right now the demand is not there for what we have,” said Glenn Johnson, president of a United Auto Workers union local at the Lordstown plant.

Last month, 61.6 percent of U.S. new vehicle sales were trucks and SUVs, according to Autodata Corp. That’s a record that is likely to be broken said Jeff Schuster, senior vice president for forecasting at the consulting firm LMC Automotive.

Because of the shift, it’s likely the GM layoffs won’t be the last at auto factories that build only cars, Schuster said. “It’s not inevitable but the likelihood is certainly higher,” he said.

Americans have been moving away from cars toward trucks and SUVs for several years now as gas prices have dropped to near $2 per gallon and the larger vehicles have become more efficient. Baby boomers and young people are attracted to smaller SUVs because of their cargo-carrying ability, high seating position and visibility.

GM doesn’t know when the workers will be called back, said spokesman Tom Wickham. .