DETROIT - For General Motors Corp., the task at hand is so difficult that experts say a Chapter 11 bankruptcy filing is all but inevitable.

To remake itself outside of court, GM must persuade bondholders to swap $27 billion in debt for 10 percent of its risky stock. On top of that, the automaker must work out deals with its union, announce factory closures, cut or sell brands and force hundreds of dealers out of business — all in three weeks.

“I just don’t see how it’s possible, given all of the pieces,â€