Postal workers' union endorses Biden

What they're saying: "This pandemic threatens the very survival of USPS. Yet, while postal employees are on the front lines providing essential services to the public every day, the current administration refuses to provide the necessary financial relief that would strengthen the agency during this pandemic," the union's president, Fredric Rolando, said in a statement.

Worth noting: Fraud from mail-in voting has historically been rare, according to the Brennan Center, with Oregon — a state that votes primarily by mail — documenting only about a dozen cases of fraud out of more than 100 million ballots since 2000.