CIT Group’s bonds and stock tumbled on concern that the Federal Deposit Insurance Corp. won’t give the commercial lender access to its Temporary Liquidity Guarantee Program.

The FDIC, which has backed $274 billion in bond sales under the TLGP since Nov. 25, has been unwilling to let CIT participate over concern that standing behind the lender’s debt would put taxpayer money at risk, according to people familiar with the regulator’s thinking.

The federal agency, run by Chairman Sheila Bair, is in discussions with CIT about how the lender can strengthen its financial position to get approval, including raising capital, said one source.

New York-based CIT’s measures to improve its credit quality, such as by transferring assets to its bank, have been insufficient, the person said.

“Sheila Bair is watching the purse,” said Mark Calabria, a director of financial regulation at the Cato Institute in Washington. “If an institution isn’t systemically important, the FDIC’s first and last viewpoint is protecting the deposit insurance fund.”