Hundreds of pro-abortion rights protests are planned nationwide Saturday in the wake of a bombshell leak of a U.S. Supreme Court draft opinion that indicated the court’s conservative majority could soon overturn Roe v. Wade.

Women’s March and Planned Parenthood are among the organizations behind more than 450 demonstrations nationwide, which are anticipated to draw hundreds of thousands of people.

Washington, D.C., is expected to be the site of the largest turnout, with 17,000 people anticipated to gather on the grounds of the Washington Monument, according to a permit issued by the National Park Service to Women’s March.