The political controversy over the fate of General Motors Corp. (GM) intensified Thursday with a simmering transatlantic dispute over the fate of its European operations.

The German government delayed a decision on supporting the partial sale of GM's Opel/Vauxhall unit until Friday, calling for more "seriousness" from the company and U.S. administration officials involved in marathon talks.

GM needs to secure the fate of its domestic and overseas operations ahead of a bankruptcy filing viewed as all but inevitable, with an announcement expected as early as May 31.

Germany delayed a decision on providing state-backed bridge financing to the Opel unit because its U.S. parent sought an extra EUR300 million in bridge financing, on top of the EUR1.5 billion already under discussion.

"What happened overnight in part borders on the absurd," German Economics Minister Karl-Theodor zu Guttenberg said Thursday.

Austrian-Canadian Magna International Inc. (MGA) and Italian auto maker Fiat SpA (F.MI) remain in the race for the Opel/Vauxhall, while financial investor Ripplewood has dropped out.

European Union industry ministers will hold a special meeting Friday to discuss GM's fate amid concerns that efforts by individual states to support GM - and preserve jobs - may challenge EU state aid regulations. GM will not be present at the meeting.

Some U.S. lawmakers are already challenging the proposed Treasury bailout of GM. The pre-packaged bankruptcy plan would give the U.S. government a stake of up to 70% in the company, in return for fresh aid.

The political machinations on both sides of the Atlantic come as GM's U.S. workers prepared to vote Thursday on a new pact that would trim wages and benefits and provide a union-run health trust with a stake in a reorganized company.

GM's bondholders have already rejected an offer to exchange their $27 billion holding for a 10% stake in the company. The company's board is due to meet before the end of the week, amid speculation that the offer to secured creditors may be sweetened to smooth its passage through bankruptcy court.

The company is widely expected to file in New York's southern court, where a judge is presiding over the case of rival Chrysler LLC.

A hearing on Chrysler's effort to exit bankruptcy with a U.S. government-backed reorganization continues Thursday.

-By Doug Cameron, Dow Jones Newswires; 312-750-4135; doug.cameron@dowjones.com

(Beate Preuschoff, Nina Koeppen, Alessandro Torello and Peppi Kiviniemi contributed to this article)