If confirmed, Ms. Yellen would become the first woman to lead a major central bank. She is 66, seven years older than Mr. Bernanke. She would be 71 by the end of a four-year term as chairwoman. But she remains in good health, and friends say that, like other prominent women of her generation, she regards herself as being in the prime of a late-blooming career. Nor would she be the oldest person to lead the Fed. Mr. Greenspan began his fifth and final term in 2004 at 78.

Ms. Yellen, slight, white-haired and described by one colleague as a “small lady with a large I.Q.,” does not loom like Paul Volcker nor cut like Mr. Greenspan. Her personal style more closely resembles Mr. Bernanke’s soft-spoken manner. The force of her arguments can catch people by surprise.

Kevin Hassett, a staff economist at the Fed when Ms. Yellen arrived in 1994, recalled that she started to eat lunch regularly in the staff cafeteria to subvert the hierarchical system that limited communication between Fed governors and the vast army of research economists. Other governors had tried to change the rules but Ms. Yellen, he said, found a way around them.

“It showed a kind of grace and wisdom that is very unusual in Washington,” said Mr. Hassett, now a fellow at the right-leaning American Enterprise Institute.

Mr. Hassett is among those who worry that Ms. Yellen does not place a sufficient emphasis on controlling inflation. “But I hold her in the highest possible regard,” he said. If the Obama administration is “going to pick a Fed chair that thinks the way they do, then Janet Yellen would be the best possible choice.”

There has been no official word from the White House or Mr. Bernanke that the Fed will have a new chairman next year. The decision is up to Mr. Obama, and aides say he has not yet focused on who he wants in the job.

But Mr. Bernanke may have signaled his departure last week when the Fed announced that he planned to skip an annual summer conference in Jackson Hole, Wyo. The Fed’s chairman has attended the event in each of the previous 25 years.