The U.S. government’s pension insurer is opposing the proposed sale of Sears Holdings to Chairman Eddie Lampert’s ESL Investments, citing a growing liability related to the entity that controls Sears biggest brands.

The Pension Benefit Guaranty Corp. (PBGC), in documents filed Saturday in U.S. Bankruptcy Court, New York, said KCD Brands  hasn’t been paid royalties since Sears filed for bankruptcy in October and administrative expenses — $86 million to date — are expected to “continue to grow.”

Yet ESL’s $5.3 billion bid to buy Sears Holdings doesn’t require the group pay those expenses as part of its offer, PBGC said. Sears sold the Craftsman brand to Stanley Black & Decker in 2017, but continues to own Kenmore and DieHard.

PBGC is the federal backstop for private retirement plans, often taking over underfunded pension plans for companies in bankruptcy. It assumed responsibility earlier this month for two of Sears’ defined benefits plans, which are 64% funded. Because PBGC will make up the difference, it is Sears’ largest unsecured creditor and joins a growing number of creditors that have objected to ESL’s offer and seek to liquidate the company.

The PBGC anticipated years ago that Sears could file for bankruptcy and that it might take over pension plans. To protect itself,  PBGC obtained an interest in the Kenmore and DieHard trademarks, it said in court documents. A hearing on Sears’ proposed sale to ESL is set for Feb. 4.