Democratic 2020 presidential candidates former HUD Secretary Julian Castro, U.S. Senator Cory Booker, U.S. Senator Elizabeth Warren, former U.S. Rep. Beto O’Rourke and Senator Amy Klobuchar pose at the start of the first U.S. 2020 presidential election Democratic candidates debate in Miami, Florida, U.S., June 26, 2019. REUTERS/Mike Segar