A campaign banner is displayed as former U.S. Vice President Joe Biden, 2020 Democratic presidential candidate, speaks during a campaign event in Des Moines, Iowa, U.S. (Photographer: Elijah Nouvelage/Bloomberg)

Biden and Trump Escalate Taunts in Preview of 2020 Iowa Battle

(Bloomberg) -- Joe Biden cast President Donald Trump as an “existential threat” to the U.S. who has weakened alliances and harmed American workers with needless trade conflicts, delivering a previe...