As Trump stands by Charlottesville remarks, rise of white-nationalist violence becomes an issue in 2020 presidential race

First came Joe Biden’s campaign announcement video highlighting President Trump’s “very fine people on both sides” comment about the 2017 white-nationalist rally in Charlottesville that left a counterprotester dead.

Then Trump dug in, arguing that he was referring not to the self-professed neo-Nazi marchers, but to those who had opposed the removal of a statue of the “great” Confederate Gen. Robert E. Lee.

Less than 24 hours later came another act of violence described by authorities as a hate crime: Saturday’s shooting at a synagogue in Poway, Calif., in which...