Mr. Trump went with the first lady — above center with a rabbi, Jeffrey Myers — and his Jewish daughter and son-in-law, who have helped shape his response to the massacre.

In the usually placid neighborhood of Squirrel Hill, now anguished by the attack, protesters gathered with messages like “President Hate is not welcome in our state.”

Meanwhile, in a new pledge to his anti-immigrant base, Mr. Trump said he would end birthright citizenship, which is guaranteed under the Constitution.

Doing so by executive order would be a highly dubious tactic, at odds with legal consensus. But ahead of midterm congressional elections on Tuesday, Mr. Trump is throwing everything at the wall, our correspondent writes.