The financially downtrodden Borders bookstore could be planning to close the 35,000-square-foot retail space in Boston’s Downtown Crossing that it has occupied for 15 years.

However, no official word of a closure has been given to Clarendon Group USA, the chain store’s landlord at 10 School St.

"We’re not absolutely certain yet that they are vacating," said Michael Murphy, director for Clarendon Group USA. "But we’ve hired CB Richard Ellis/Grossman Retail Advisors to market the space within the last few days. We hired them due to their national and international ties to cast a wide net for tenants … if we need to release [the space]."

"I guess my gut would tell me they may be leaving, but I would say the door’s still open," he added.

Borders’ lease runs until January. However, the company entered bankruptcy proceedings early this year. That provides the company the choice to accept and acknowledge its lease, or to reject it without penalty, Murphy added.

Borders has paid the same rental rate in the downtown space since the lease was written in 1995, making it likely substantially below market value. That is unlike most retail leases, which allow for increases at pre-determined times over the life of the lease, Murphy said.

It is too soon to talk about what tenant, or what type of tenant, would best fit the space, Murphy maintained.

Borders has shuttered more than 200 stores nationwide as the chain struggled through the recession. It is the second major bookstore, after Barnes & Noble, to close a Downtown Crossing location near the former Filene’s site, where construction on a mixed-use development halted nearly three years ago and left a crater in the middle of the shopping district.