For General Motors, the task at hand is so hard that experts say a 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,” said Stephen J. Lubben, a professor at Seton Hall University School of Law who specializes in bankruptcy.

GM, which has received $15.4 billion in federal aid, faces a June 1 government deadline to complete its restructuring plan. If it can’t finish in time, the company will follow Detroit competitor Chrysler LLC into bankruptcy protection.

Although company executives said last week they would still prefer to restructure out of court, experts say all GM is doing now is lining up majorities of stakeholders to make its court-supervised reorganization move more quickly.

The threat of bankruptcy, however, may be just a negotiating ploy to pull reluctant bondholders into the equity swap deal. In Chrysler’s case, some secured debtholders resisted taking roughly 30 cents on the dollar for what they were owed, but most gave in after they were identified in court documents.