Mr. Mnuchin, testifying before Congress, said new security features under development made the 2020 design deadline set by the Obama administration impossible to meet, so he punted Tubman’s fate to a future Treasury secretary.

In fact, work on the new $20 note began before Mr. Trump took office, and the basic design already on paper most likely could have satisfied the goal of unveiling a note bearing Tubman’s likeness on next year’s centennial of the 19th Amendment, which granted women the right to vote. An image of a new $20 bill, produced by the Bureau of Engraving and Printing and obtained by The New York Times from a former Treasury Department official, depicts Tubman in a dark coat with a wide collar and a white scarf.

That preliminary design was completed in late 2016.