The future of Vauxhall and Opel is now expected to be announced tomorrow (Thursday).
An announcement of GM's preferred bidder for the company had been expected late today, but sources suggest it will now be delayed slightly as details are hammered out and agreement is reached with the German government.
Britain and Germany have indicated they will provide state aid to Vauxhall and Opel in the event of a sale.
Lord Mandelson that Britain said Britain had "not ruled out making a financial contribution" to help to save Vauxhall.
Mandelson added that he had held "substantial telephone conversations" with Fritz Henderson, GM's chief executive, and Carl Peter Forster, chief executive of GM Europe, and had made clear "the UK’s commitment to all of Vauxhall’s plants."
He has also met Fiat and Magna to seek reassurance as he lobbies to prevent the German government from giving in to election-year pressure with a pledge to protect domestic jobs at the expense of the UK.
Meanwhile, Peer Steinbruck, the German Finance Minister, said that it was "quite possible" that Germany would provide emergency financing to Opel.
"The time plan will depend on decisions made in the United States," he said, referring to GM's anticpated move into Chapter 11 bankruptcy protection on or before 1 June.
Yesterday Beijing Automotive Industry Corporation (BAIC) was confirmed as a bidder to buy both Opel and Vauxhall. Fiat, the Italian carmaker, Magna, of Canada, and RHJ, of Belgium, are the other bidders in the race.
BAIC has pledged not to cut any jobs or close plants in Germany for two years. It also has plans to inject 700 million Euros (£615 million) into Opel and use less state money than the other bidders have requested.