General Motors Corp. (GM) announced Thursday plans to temporarily idle 13 North American factories this summer, slashing production by 190,000 vehicles as it races to shrink bloated inventories. GM said the shutdown also will help protect against an unplanned work stoppage the company worries could result from stalled negotiations over bankrupt parts maker Delphi Corp. (DPH).

The move comes as GM struggles to stay afloat on government loans and faces a deadline imposed by the Obama administration to dramatically restructure or go bankrupt by June 1.

Halting production will further erode revenue for GM, burning through billions in the worst sales environment in decades. GM's sales are down 40% through March compared to last year. The cost of continuing to pump out cars and trucks, however, would be greater.

The auto maker is saddled with excess inventories, which already are heavily discounted.

"By reducing our inventories even more aggressively we reduce pressure on GM and our dealers, and set ourselves up well for a clean 2010 model year start-up," Troy Clarke, GM North America president, said.

GM said the downtime also will protect the company against a parts shortage should Delphi, the company's former parts arm, fail to continue operating. The auto maker, in a news release, said lenders to Delphi have rejected a proposal that would resolved Delphi's bankruptcy case and ensure supply of parts to GM.

"Without the successful resolution of this dispute, it is General Motors' view that Delphi or its lenders could force GM into an uncontrolled shutdown, with severe negative consequences for the U.S. automotive industry," the release said.

GM's hourly workers, represented by the United Auto Workers, will get most of their pay during the shutdown from a combination of state unemployment benefits and payments from GM.

-By Sharon Terlep, Dow Jones Newswires; 248-204-5532; sharon.terlep@dowjones.com.