PITTSBURGH (AP) — One stone and one white rosebud for each victim.

President Donald Trump and first lady Melania Trump paid homage Tuesday to each of the 11 people slain in the worst instance of anti-Semitic violence in American history. As the Trumps placed their tributes outside the Tree of Life synagogue, protesters nearby shouted that the president was not welcome.

The emotional, dissonant scene reflected the increasingly divided nation that Trump leads, one gripped by a week of political violence and hate and hurtling toward contentious midterm elections that could alter the path of a pre...