WASHINGTON — The more the chief executive of Wells Fargo tried to explain, the more skeptical the senators became.

For more than two hours testifying before the Senate Banking Committee on Tuesday, John G. Stumpf expressed regret that Wells Fargo had created as many as two million bogus bank and credit card accounts without its customers’ consent. He apologized for failing to stop the illicit behavior sooner, and vowed to make amends.

Some of the senators on the committee scoffed. Mr. Stumpf, they said, was offering little more than platitudes while allowing his top executives to avoid any real consequences — like being fired or having their enormous pay packages clawed back.

Instead, the bank’s lowest-paid workers have borne the brunt of the punishment, the senators noted. Senior management, they said, seemed to ignore this practice because it helped turn the bank into a profit machine.