The last time the portraits on America’s paper currency got a major renovation was in 1928, when Andrew Jackson replaced Grover Cleveland as the face of the $20 bill. Nearly 90 years have passed since then, and the advocacy group Women on 20s is arguing that it’s high time for another change. Specifically, they say, it’s time to break with the all-white male tradition and put a woman’s face on U.S. currency. For the past several months, the group has been conducting a grassroots campaign to replace Jackson with a prominent American woman by 2020, the 100th anniversary of female suffrage.

Sound like a crazy idea? Maybe not. A similar campaign in Britain led the Bank of England to announce back in 2013 that Jane Austen will soon appear on the 10-pound note. The U.S. campaign already has powerful backing: Last month, Senator Jeanne Shaheen of New Hampshire introduced a bill asking to convene a citizen panel to discuss putting a woman’s face on U.S. paper money. The panel would send its findings the Treasury Department, led by Treasury Secretary Jack Lew, which has control over any changes to U.S. currency.

As part of their grassroots campaign, Women on 20s chose an initial list of 15 notable American women—including Red Cross founder Clara Barton, suffragist leader Susan B. Anthony, feminist author Betty Friedan and Shirley Chisholm, the first African-American women elected to Congress—and asked the public to weigh in via an online survey. (Anthony used to appear on the $1 coin, and was later replaced by an image of Sacajawea, the Native American guide of the explorers Lewis and Clark. No woman has appeared on U.S. paper currency since Martha Washington, whose image was printed on $1 silver certificates in the late 19th century.) From that list, the group was narrowed to four finalists: Tubman, former First Lady Eleanor Roosevelt, civil rights pioneer Rosa Parks and Wilma Mankiller, the first female chief of the Cherokee Nation. Tubman received 118,328 votes in the final poll, about 7,000 more than Roosevelt, the runner-up.

Born into slavery in Maryland around 1820, Harriet Tubman escaped across state lines to Delaware and then Pennsylvania around 1849. As she never learned to read or write, historical documentation about her life is limited, but it is known that she joined the Union Army during the Civil War, working as a laundress, cook and nurse. She was eventually recruited as a Union spy, and in June 1863 helped Col. James Montgomery lead a raid at Combahee River in South Carolina that freed some 750 slaves. Tubman was also the most famous conductor of the Underground Railroad, the abolitionist network that ferried slaves to freedom in the North and Canada.

In addition to recognizing Tubman in particular, and American women in general, on the 100th anniversary of female suffrage, changing the face on the $20 would also address persistent criticism of Jackson. The seventh president was outspoken in his support of government policies against Native Americans, including the infamous Indian Removal Act of 1830, which led to the massive forced relocation known as the “Trail of Tears.”

In all, more than 600,000 people voted in the online survey, a formidable number that Women on 20s hopes will bring some weight to the petition it now plans to send to President Barack Obama. The next step is a so-called “Virtual March” on Washington, using the social media hashtag #DearMrPresident. As Susan Ades Stone, executive director of Women on 20s, told the Washington Post: “Our work won’t be done until we’re holding a Harriet $20 bill in our hands in time for the centennial of women’s suffrage in 2020.”

In a speech last July, before the launch of the voting campaign, Obama said that putting a woman on U.S. currency was a “pretty good idea.” But even if the president does choose to use his influence, any change in the design of the $20 bill—or any U.S. currency—will ultimately be the decision of Secretary Lew and the U.S. Treasury Department.