In Northeast Florida, several hundred enthusiastic Republicans flowed into Jacksonville’s Prime Osborn Convention Center on Friday for a two-day conference headlined by Donald Trump Jr., the former president’s son. The American Freedom Tour, a showcase of high-profile political conservatives, continued Saturday with a slate of politicians, commentators and political celebrities. People turning out Friday represented “the backbone of the Republican Party” in Northeast Florida, according to a retired University of North Florida government documents librarian, who said curiosity drew him there. The former librarian saw a large meeting room where most of the seats were taken. It suggested organizers had connected with an audience hungry for messages like Trump Jr.’s talk on “How to Win Back America.”