Step by step, the taxpayer is being drawn into paying for bank failures.

On one front, the Federal Deposit Insurance Corp. wants Congress to expand its line of credit at the Treasury in case the cost of bank failures exhausts the fund.Theoretically, banks would repay the loan through an increase in their insurance premiums. But if the industry continues to deteriorate, taxpayers are at risk.

Separately, support is growing for having taxpayers, rather than the banking industry, bear the extra cost of bailing out uninsured depositors in institutions whose failure could unravel the financial system.

Sen. Donald W. Riegle Jr., D-Mich., chairman of the Senate Banking Committee, introduced a broad banking overhaul bill this week. One provision, in effect, would have taxpayers share the cost of the biggest bank rescues.

His bill is intended to prevent bank failures with tougher regulation and would bar the FDIC, which is financed by the industry, from protecting deposits in excess of $100,000 after 1994.

However, the Federal Reserve could pay off uninsured depositors if it believed that was necessary to prevent a contagious run on other banks' deposits or some other extreme financial emergency.

Any money the central bank spent would have to be deducted from the annual revenues it forwards to the Treasury. So, in effect, general taxpayers would bear the cost.

The proposal could prove politically touchy, especially with so many members of Congress being attacked by constituents over the multibillion-dollar taxpayer bailout of the savings and loan industry.