The Federal Reserve governor Jeremy C. Stein is the chairman of the internal committee that monitors financial markets for signs of trouble, and of the committee that watches the way that banks treat their customers.
He is also the only remaining member of those committees.
Mr. Stein has said that on May 28 he will step down from the Fed.
A string of departures from the Fed's seven-member board over the last year has left the central bank on the verge of operating with just three governors for the first time in its 100-year history. Three nominees are awaiting Senate confirmation, but so are scores of nominees to other offices, and Senate Democrats say there is a real chance no vote will be held before Mr. Stein departs at the end of this month.