In May, Mr. Mnuchin said at a congressional hearing that the design imagery of the bill would not be ready until 2026 because of the complexity of creating new anti-counterfeiting measures. He would not commit to Tubman ever appearing on its face and said that a future Treasury secretary would make that decision.

Mr. Mnuchin has denied delaying the process and said in a statement last week that Treasury and the Bureau of Engraving and Printing remain committed to the schedule of new $20 notes going into circulation by 2030.

Len Olijar, the director of the bureau, said that, for security reasons, design concepts of a new $20 note were never going to be released next year and that “everything remains on the table” regarding whose portrait will be on the new bill. Mr. Olijar said that the image of a $20 note that The Times obtained featuring Tubman’s portrait, which was created by the bureau, was not an advanced design concept.

After Mr. Trump took office, the Treasury Department removed from its website all mentions of Tubman or the planned changes to the $20, $10 and $5 notes that the Obama administration set in motion. Mr. Mnuchin had said little on the subject until he was pressed about it during a House Financial Services Committee hearing last month.

The delay of the new design has prompted calls for the Trump administration to follow through in adding Tubman to the note and bipartisan legislation in the House that would require the Treasury Department to do so next year.

Requests from Congress for inspector general inquiries do tend to yield responses. Mr. Mnuchin’s department has faced internal investigations into the secretary’s travel practices and into his handling of an analysis of the Republican tax cut legislation. The inquiry into Mr. Mnuchin’s air travel found he broke no laws in his use of military aircraft but lamented the loose justification provided for such costly flights. The tax cut analysis investigation found no evidence of any improper political interference with the career tax staff.