The clock is ticking for Borders Group Inc., pioneer of the big box bookstore that is facing almost certain liquidation if a 'white knight' investor does not surface within a matter of hours.

Borders filed for bankruptcy in February 2011 after the brick-and-mortar store fell behind on its financial obligations. A bankruptcy court auction is scheduled for Tuesday, and the lead bid is currently held by a group of liquidators lead by Hilco Merchant Resources.

The deadline for offers that might keep Borders operating passed on Sunday at 5 p.m., with no potential investors providing sufficient bids to keep Borders a going concern.

An article in the Wall Street Journal predicted that Borders is likely to entertain offers right up until the scheduled auction in the hopes a white knight will emerge to save the chain.

Until it dissolved last week, Borders had a deal in place with investor Jahm Najafi, who had offered $250 million for the bookstore chain, along with a commitment to assume $220 million in liabilities.

His offer was ultimately passed over by a creditor committee, who concluded that liquidation would be a better deal.

Sarah Weinman of Publishers Marketplace posted a Twitter message on Thursday saying that while the bankruptcy judge accepted the liquidator bid, objections could be submitted until Monday afternoon.

Books-A-Million, a Birmingham-based bookstore chain, has offered to buy a small number of Borders' retail locations. Reuters reports that the number is less than 50, which would still mean the closure of hundreds of locations.

Borders has already closed more than a third of its stores since filing for bankruptcy, leaving only 399 stores in operation. 

Borders has about 5,300 employees; half are full-time.