GM has postponed making a decision on who will buy Vauxhall and Opel.
GM's directors met last Friday to discuss the sale, but announced that "no decision was taken".
The race to control Vauxhall and Opel is between the Canadian component manufacturer Magna and Belgian financial group RHJ.
The delay is reported to be down to last-minute conditions to any deal added by the German government, which will provide a £3.9 billion bridging loan to the company that buys Vauxhall/Opel.
The German government has repeatedly favoured Magna's bid as it will result in fewer job losses in Germany, and is reported to be offering more lenient loan terms if GM picks it as the buyer.
UK business secretary Lord Mandelson has been critical of German chancellor Angela Merkel for politicising the bidding contest.
Earlier this week Lord Mandelson said GM needed to look for an "industrial outcome based on the long-term viability" of Opel.