The fate of ailing American auto giant General Motors and its German-based Opel unit could be decided in a matter of days.

GM is surviving on about $19 billion in emergency loans from the U.S. government, and faces a June 1 deadline to drastically cut costs and restructure the company or declare bankruptcy.  But the automaker's future could depend on decisions by its U.S. workers and by debt-holders over the next few days.

Leaders of the union representing GM's U.S. workers approved an agreement Tuesday that would save the automaker hundreds of millions of dollars.  Members still need to ratify the deal this week.  

Debt-holders must decide by the end of Tuesday whether to exchange the right to collect $27 billion in debt for a 10 percent stake in a restructured company, but many already have rejected the proposal.

GM also is trying to sell its Opel unit to one of three bidders in an effort to raise money.  German government officials say they could announce their preference as early as Wednesday.

Italian automaker Fiat, Canadian parts maker Magna International and Brussels-based investment firm RHJ are trying to acquire Opel, which employs about 25,000 people in Germany.

Fiat chief executive Sergio Marchionne met with German Chancellor Angela Merkel about his company's proposal Tuesday.  But German Economy Minister Karl-Theodor zu Guttenberg said all three companies need to improve their offers.

Fiat already is in the process of merging with Chrysler, the number three U.S. car maker, which has filed for bankruptcy.  Acquiring Opel would turn Fiat into one of the world's biggest auto companies.

Media reports say a Chinese company also may try to submit a last-minute bid to buy Opel.

Earlier Tuesday, GM won major concessions from its Canadian workers.

The Canadian Auto Workers (CAW) union ratified a new contract with GM that cuts hourly wages for new hires by $13-14, and freezes retiree pension payments until 2015, but keeps GM plants in Ontario province open.  

The Washington Post has reported that the Obama administration is preparing to push GM into bankruptcy this week.

Some information for this report was provided by Reuters.