Democrat Joe Biden is assailing President Donald Trump on trade and broadly branding him as “existential threat to America” in a preview of what the country might expect if he prevails in his party’s primary contest. The president, also coming to Iowa on Tuesday, was likely to have some choice words in response. Biden was expected to zero in on the economy— an issue the president often promotes as his chief strength in a time of low unemployment — during a speech in Davenport, a center of eastern Iowa’s agricultural manufacturing industry.
