By July, in fact, Mr. Lew already had decided to keep his long-ago predecessor on the $10 note, and put a vignette of suffragists on the back, with Tubman scheduled for the $20 bill and changes to the $5 note as well.

“I had a kind of ‘aha’ moment where I said we’re thinking too small,” Mr. Lew said on Wednesday.

He decided to redesign all three notes to accommodate the various views, and sooner. As for the choice of Tubman, he said that in the public comments he reviewed each night, “the pattern became clear that Harriet Tubman struck a chord with people in all parts of the country, of all ages.”

“This is a good solution,” said Senator Susan Collins, Republican of Maine, who wrote to the secretary “strongly suggesting he not remove Hamilton” from the bill.

Image Harriet Tubman’s death announcement in the The New York Times in 1913.

Mr. Lew directed the Bureau of Engraving and Printing to hasten the redesign of the $20 and $5 notes at the same time. Subsequent production of the $10 bill would take precedence, though Mr. Lew said all three notes could be in wallets before 2030. The final decision on release is up to the Fed.

One wild card is that Mr. Lew and President Obama have just months left in office. But Mr. Lew expressed confidence that his successors would not veto the currency makeovers.

“I don’t think somebody’s going to probably want to do that — to take the image of Harriet Tubman off of our money? To take the image of the suffragists off?” he said.