Italy's Fiat , car parts group Magna and investment firm RHJ were all expected to submit offers for Opel, the German unit of U.S. carmaker General Motors , by a Wednesday deadline.

A spokesman for GM Europe said the company believed it would receive at least three bids for Opel, which employs 25,000 staff in Germany and whose fate is being closely followed by the government in Berlin ahead of a federal election in September.

Both GM and Germany are in a race against time as the U.S. parent seeks emergency aid from the U.S. government and nears a June 1 deadline to restructure its bond debt and reach a deal with its major union.

It has asked bidders for Opel to submit their offers by Wednesday at 6 p.m. (12 p.m. EDT). Although GM will decide which investor gets Opel, it has said the German government will play a big role because it would likely provide billions of euros in financing to help any buyer.

Italian carmaker Fiat , which recently agreed to take a stake in U.S. carmaker Chrysler, would like to add Opel and other GM Europe assets to the mix to create the world's second-largest auto group behind Japan's Toyota <7203.T>.

Magna, a Canadian-Austrian car parts company, is also interested in Opel, most likely in cooperation with Russian investors.

It has proposed opening up under-used Opel plants to other automakers and allowing them to use Opel platforms to bring niche models to market quickly.

Belgium-based holding company RHJ International is also expected to bid, a financial source told Reuters.

TOP-LEVEL GERMAN MEETING

German Chancellor Angela Merkel met with top cabinet members on Wednesday to discuss Opel's future after Fiat CEO Sergio Marchionne traveled to Berlin on Tuesday evening and met with government officials regarding his bid.

Should GM be forced into bankruptcy, the German government is keen to shield Opel from creditors until a buyer is finalized. It wants to place Opel assets with a trustee and provide bridge financing for the group until a deal is completed.

On Tuesday the government brokered an agreement whereby state-bank KfW and the four German states with Opel plants will supply about 1.5 billion euros in financing to tide the carmaker over until a buyer for Opel is settled upon.

Speaking in Berlin after the government meeting, Labour Minister Olaf Scholz said preliminary decisions on Opel must be made by the beginning of next week.

We don't have much time. Decisions must be made this week, or at the latest by the start of next week, Scholz told a news conference.

Earlier, Italy's industry minister said he believed Fiat had good possibilities to close a deal with Opel. But a spokesman for the German economy ministry said the competition was open-ended and that Berlin had no favorites.

Opel unions are skeptical about the Fiat bid, fearing their overlapping product ranges could spell plant closures in Germany, Austria, Britain or Belgium.

Opel labor leader Klaus Franz told Reuters in an interview that a final deal for Opel could take several weeks but he did not exclude the possibility that a letter of intent could be presented this week.

It will be a crucial issue whether an investor submits a memorandum of understanding which then would form the basis for further negotiations, he said. I expect more offers than just from Fiat and Magna.

GM Europe head Carl-Peter Forster told German magazine auto motor and sport that the sale process could last until the fourth quarter of this year.

He said Opel's liquidity would last into the third quarter, and emphasized that the German carmaker would not be part of any Chapter 11 process by GM.

($1=.7334 Euro)

(Reporting by Frankfurt, Berlin, Milan, Paris, London bureaus, Editing by Jason Neely)