Joseph R. Biden defeated Sen. Bernard Sanders in the Arizona primary, marking a three-state sweep for the former vice president on Tuesday and giving him what could prove to be an insurmountable lead in the 2020 Democratic presidential race.
Mr. Biden has been a roll since turning his campaign around late last month with a victory in South Carolina.
Since then he has won an overwhelming majority of the contests and has left Mr. Sanders with the narrowest, if any, path to the nomination.
Please read our comment policy before commenting.