General Motors Corp. could be majority owned by the federal government and the United Auto Workers under a massive restructuring plan laid out Monday that will cut 21,000 US factory jobs by next year and phase out the storied Pontiac brand. The plan, which includes an offer to swap roughly $27 billion in bond debt for GM stock, would leave current shareholders holding just 1 percent of the century-old company, which is fighting for its life in the worst auto-sales climate in 27 years. GM is living on $15.4b. in government loans and said Monday in a filing with the US Securities and Exchange Commission that it envisions receiving an additional $11.6b. But if GM's restructuring plan can't satisfy the government by June 1, the struggling company could go into bankruptcy protection. GM said it would ask the government to take more than 50% of its common stock in exchange for canceling half the government loans to the company as of June 1. The swap would cancel about $10b. in government debt. In addition, GM is offering the UAW stock for at least 50% of the $20b. the company must pay into a union-run trust that will take over retiree health-care expenses starting next year. If both are successful, the government and UAW health-care trust would own 89% of GM stock, with the government holding more than a 50% stake, CEO Fritz Henderson said in a news conference at GM's Detroit headquarters. President Barack Obama's administration said in a statement that the bond-exchange filing was an important step in GM's restructuring, but the administration has not made a final decision about taking stock for part of its loans. Henderson said although the government would own a majority of GM's outstanding common shares, the Treasury "hasn't demonstrated interest in running the company," but would have someone on the board looking out for the taxpayers' interest. The task force has directed current board chairman Kent Kresa to replace several board members. Deals with the UAW and the Treasury have yet to be finalized, he said. The struggling automaker said it would offer 225 shares of common stock for every $1,000 in notes held by bondholders as part of a debt-for-equity swap. Henderson said the objective was to reduce GM's $27b. of outstanding public debt by about $24b. The company estimates that after the exchange, bondholders would own 10% of the company. That would leave current common stockholders with only 1%, GM said. Still, GM shares rose 47 cents, or 27.8%, to $2.16 in midday trading. The plans, if successful, would reduce GM's debt by $44b. from the present figure of about $62.4b. Henderson said if the debt exchange isn't successful, he would expect GM to file for bankruptcy protection somewhere around June 1, but such a filing would be unlikely very long before the deadline. Bondholders have until May 26 to accept the exchange offer. Henderson said the company still preferred to restructure outside of court, but he acknowledged that the prospect of bankruptcy is more likely now that it was a few weeks ago. GM said it would speed up six additional factory closings that were announced in February, although it did not identify the locations. Additional salaried jobs cuts also are coming, beyond the 3,400 in the US completed last week. Henderson said there would be three more factory closures in 2010 beyond the six that were previously planned. Including previously announced plant closures, the restructuring will leave GM with 34 factories at the end of next year, 13 fewer than it had at the end of 2008. Besides the US job cuts, General Motors Canada said it plans to slash its hourly work force from 10,300 to 4,400 by 2014. The company also said it plans to reduce its dealership ranks by 42% by 2010, cutting them from 6,246 to 3,605. The company said it would phase out Pontiac no later than next year, and the futures of Hummer, Saturn and Saab will be resolved by the end of this year by either selling them or phasing them out. For Pontiac, the decision means the death of a brand known for its muscle cars, including the Trans Am made famous in movies, and the GTO, the subject of a nostalgic song by Ronny and the Daytonas. Henderson said in a news conference that the company was spread too thin to make Pontiac work. He said the decision was very tough for many at GM because of the 83-year-old brand's heritage.