A General Motors Corp. bankruptcy filing seemed inevitable after a rebellion by its bondholders forced it to withdraw on Wednesday a plan to swap bond debt for company stock.

GM has until Monday to complete a government-ordered restructuring that includes debt reduction, labor cost cuts and plant closures. But a Chapter 11 reorganization is likely after the company said its offer to exchange $27 billion in unsecured debt for 10 percent of the company's stock had failed. GM has received $19.4 billion in federal loans.

The move came as crosstown rival Chrysler LLC headed to court Wednesday to ask bankruptcy judge for permission to sell the bulk of its assets to a group headed by Italy's Fiat Group SpA in hopes of saving itself from liquidation. Attorneys for Chrysler maintain that the Fiat deal is the company's only hope to avoid being sold piece by piece, but car dealers, debtholders, former employees and others are protesting.

Chrysler filed for bankruptcy protection April 30, after the government ended talks with a group of holdout debtholders. Both automakers were pulled down by overwhelming debt, high pension, health care and other labor costs relative to competitors, a global auto sales slump and a dismal U.S. housing market that pulled down demand for pickup trucks, their top-selling vehicles.

News of the failed GM bond exchange offer sent its shares down 12 cents, or 8.3 percent, to $1.32 in morning trading.

John Pottow, a professor at the University of Michigan who specializes in bankruptcy, said GM evading Chapter 11 now is almost impossible.