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.