Delphi Corp's ability to sell itself depends on four of its loss-making plants that buyers may need to inherit as part of a sale, the New York Post said on Wednesday.
Talks between Delphi and its lenders have been progressing toward a compromise deal that would supersede a bid by private equity firm Platinum Equity favored by GM and the U.S. Treasury, sources told Reuters last week.
On Wednesday the New York Post cited a source as saying rival bidders have not received a similar assurance from GM about the plants.
On July 21 a federal judge postponed the auction for the assets of the bankrupt auto parts maker a second time, so as to give bidders more time to work out a deal.
The company, which has been in bankruptcy protection since 2005, was spun off by automaker General Motors in 1999 and is its largest supplier.
Delphi was not immediately available for comment.
(Reporting by Nivedita Bhattacharjee in Bangalore; Editing by Greg Mahlich)