The issues the banking committee want to know more about include: officially identifying the independent directors serving on the bank’s internal investigative committee; why such an investigative committee wasn’t in place before the settlement; how it will make its report known to shareholders and the public; what was the board’s knowledge of the scandal before Sept. 8; and what other business lines had been affected by the fraudulent employee behavior.

The senators want answers by Jan. 6.

“As you know, continued failure to answer questions — especially basic questions — about the causes and consequences of the fraud that Wells Fargo permitted for many years does nothing to restore the trust of Wells Fargo’s customers and shareholders, many of whom are our constituents,” the senators wrote.

Analysts say the shadow over the bank will not go away until it discloses more information about the depth of the scandal, and what management and the board knew about it and when they were told. Analysts have questioned whether some board members will be required to step down as part of the rehabilitation process.

“In our view, waiting until Spring 2017 to provide more documents and information to our questions is not diligence,” the senators wrote.