With the passage of the Nineteenth Amendment, the right to active participation in American representative democracy had legally reached all adult citizens over twenty-one. In the wake of this success, in 1923 Alice Paul drafted and began campaigning for the ratification of an Equal Rights Amendment (ERA) to guarantee federal protection under the law for both sexes. Although a few states ratified the ERA, the momentum of the suffrage movement slowed, and soon the Depression and World War II led Congress and the public to focus on more immediate and pressing concerns. –The Smithsonian’s History of America in 101 Objects,
Richard Kurin

Based on the passage, which event or events caused Alice Paul to begin campaigning for the federal ERA?