DETROIT - The worsening U.S. auto sales slump claimed 2,000 more workers today as General Motors Corp. announced layoffs at three more car factories.

The company said it will cut shifts at car factories in Lordstown, Ohio; Orion Township, Mich.; and Oshawa, Ontario, starting in February due to slowing demand for their products.

"It's all market driven, as all of our changes have been of late," spokesman Chris Lee said.

In Lordstown, where GM makes the Chevrolet Cobalt and Pontiac G5 small cars, 890 workers will go on indefinite layoff starting Feb. 2 when GM ends a third shift at the sprawling complex. The shift was added earlier this year when gas prices hit $4 per gallon and demand for small cars skyrocketed.

Also Feb. 2, GM will lay off 390 workers by cutting a third shift at the Orion plant near Pontiac. The factory makes the Chevrolet Malibu and Pontiac G6 midsize sedans. The Malibu had been GM's hottest seller, but demand has started to wane in recent months. No date has been set to bring the workers back because GM doesn't know when sales will return.

And 700 more workers will go on indefinite layoff Feb. 9 in Oshawa, Ontario, where GM makes the Chevrolet Impala large sedan. The company is cutting the third shift, also due to slowing demand, Lee said.

GM also is adding several weeks of down time to the normal two-week holiday shutdown that will essentially keep the Lordstown and Orion plants closed from late December through the month of January.

In addition, GM is adding a week of down time at its Malibu and Saturn Aura plant in Kansas City, Kan., keeping it closed for three weeks in January. When workers return Jan. 26, the assembly line speed will be slowed, Lee said.

GM's U.S. sales fell 41 percent in November when compared with the same month last year, and they are down 22 percent for the first 11 months of the year.

Overall, U.S. sales were off 37 percent in November, the worst level in 26 years, and were down more than 16 percent so far this year.

Automakers have blamed tight or nonexistent credit, economic woes and a lack of consumer confidence for the slump, and they aren't predicting much of a recovery in 2009.

GM shares fell 10 cents to $4.01 in morning trading today. They have traded in a range of $1.70 to $29.28 over the past year.