But some worry that the agency has fewer people  and less money  than it needs to cope with the industry’s latest travails, particularly if several large institutions were to collapse. Nine lenders, most of them small, have failed so far this year. Analysts expect dozens more to run into trouble.

Ms. Bair’s agency is stretched. Dozens of staff members who had been through the banking crises of the early 1990s retired in recent years. Despite her efforts to bring some seasoned examiners back, her small army of examiners is largely untested.

Meanwhile, there are growing questions about the adequacy of F.D.I.C.’s insurance fund, which guarantees repayment on deposit accounts of up to $100,000 when banks collapse. The fund dwindled to $45.2 billion during the second quarter, from $53 billion in the first quarter.

To replenish its fund, the agency will probably have to raise the fees it charges banks by at least 14 cents for every $100 of deposits, according to estimates by analysts. Ms. Bair declined to comment on the likely size of any increase but said the agency was proposing to revamp its fees so that institutions engaging in high-risk practices would pay higher rates.

“It only seems fair,” Ms. Bair, 54, said. Such a move is expected to draw criticism from banks.

How Ms. Bair navigates the financial and political landmines ahead will help determine the course of the banking industry and, by extension, the broader economy. It will also determine her legacy.

“If the agency gets through the credit mess, having handled the bank failures that are to come, she is going to be widely seen as the person who prepared the agency for this,” said Jaret Seiberg, a financial policy analyst for the Stanford Group in Washington. “If the cycle is worse than expected  and if the agency insurance fund isn’t big enough or they didn’t have enough examiners  she will become the fall guy.”

Image Sheila C. Bair of the Federal Deposit Insurance Corporation. Credit... Daniel Rosenbaum for The New York Times

The centerpiece of Ms. Bair’s plan is to modify loans so that people can stay in their houses. “It is something we should put a priority on,” said Ms. Bair, who speaks at a rapid clip.