Federal regulators will permit the financing arm of General Motors to become a bank and gain access to billions of dollars in government aid, a crucial step that will help ensure the survival of the company.

In a 4 to 1 vote, the Federal Reserve Board approved GMAC’s application to transform itself into a bank holding company “in light of the unusual and exigent circumstances” affecting the financial markets. The move will allow GMAC to tap as much as $6 billion in government bailout money. The approval came as GMAC bondholders were facing a Friday deadline to vote to approve a complex transaction that would significantly reduce the company’s outstanding debt.

As of Dec. 17, bondholders had agreed to convert less than 60 percent of their debt into preferred shares. Some big bondholders like the investment firm Pimco have said they do not intend to exchange bonds unless Cerberus Capital Management  the private equity firm that owns 51 percent of GMAC  puts more money into the company.

GMAC has been hit with huge losses in both its mortgage and auto loan businesses. The approval from federal regulators may help persuade remaining bondholders and should make it easier for the company to raise money. It should also help General Motors, which owns a minority stake in GMAC and depends on the firm to finance some of its cars.