German politicians said Friday that no decision has been made yet on the three bids for General Motors Corp.'s (GM) troubled Opel brand, but Austria-Canadian auto supplier Magna International Inc. (MGA) appears to be frontrunner despite the state of North Rhine Westphalia's objections.

"All options are still under consideration ... I very much call for keeping all three [bids] in the talks," zu Guttenberg told Dow Jones Newswires on the sidelines of an event in Berlin, noting that insolvency was also still an option.

Separately, zu Guttenberg described Magna's bid for Opel as "interesting," but added that some financial details still require clarification as the German state is expected to support the deal with taxpayers' money.

"It is the case that Magna has presented an interesting concept, but also [one] that has drawn up questions. These are all questions that are relevant to taxpayers," he said.

The federal government and the states of Hesse, North Rhine-Westphalia, Thuringia and Rhineland Palatinate, which are home to Opel plants, are considering bridge financing to keep opel operating if GM files for insolvency before it can be sold.

The financing, which will only be given if the government and the states regard at least one of the bids as sustainable, aims to give Opel more time for negotiations with the potential investors. The bridge, or interim, financing of around EUR1.5 billion would be from state-owned bank KfW and Landesbanken of the states with Opel plants.

Apart from Magna, Italian automaker Fiat SpA (F.MI) has launched a bid for Opel as part of a wider push to forge a global auto alliance comprising its own auto unit as well as Chrysler LLC.

RHJ International (RHJI.BT), a European buyout firm of investor U.S. Ripplewood with holdings in the auto-parts industry, is also in the race.

The governor of North-Rhine Westphalia, Juergen Ruettgers, said he won't support Magna's bid as 2,200 from a total of about 10,000 job cuts would be axed at Opel's Bochum plan, which is located in his state. He admitted, however, that Magna's bid is "the most detailed one."

The governors of the German states of Thuringia, Rhineland Palatinate and Hesse earlier voiced support for Magna's bid.

German Vice Chancellor Frank-Walter Steinmeier echoed remarks by Economy Minister zu Guttenberg, saying that no final decision has been made. He said, however, that during a meeting at the German chancellery earlier Friday it has been agreed that clarifying some details regarding Magna's bid has priority.

German politicians are planning to continue to discuss the bids for Opel at a meeting on Monday, he said.

"It is safe to say that whichever concept we might want to pursue, a substantial number of jobs in Europe is at risk," zu Guttenberg said. Regarding a timeframe for a decision, zu Guttenberg said: "We must have made a principle decision next week because in the U.S. they will make a decision regarding starting insolvency procedures" for Opel's parent, GM.

-By Andrea Thomas and Christoph Rauwald, Dow Jones Newswires; +49 69 29 725 512; christoph.rauwald@dowjones.com