WASHINGTON — Amid the storm of criticism over his response to the synagogue killings in Pittsburgh and the accusations that his messaging created the atmosphere that caused them, President Trump has turned to the people he trusts most for advice — his family.

His son-in-law, Jared Kushner, who keeps a photograph of his grandparents, both Holocaust survivors, in his West Wing office, and a mezuza on the doorway, as well as his daughter Ivanka, who converted to Judaism to marry Mr. Kushner, have quietly and persistently shaped the president’s response to one of the nation’s deadliest cases of anti-Semitism.

In the immediate aftermath of the shooting on Saturday, their conversation with the president led to a marked change in his language. Within hours, his remarks went from a vague statement — “if they had an armed guard inside, they might have been able to stop him immediately,” he said — to a plea to a rally crowd in Illinois to combat “the scourge of anti-Semitism.”

It was their advice to go to Pittsburgh on Tuesday despite the opposition of city officials and many members of the Jewish community. To lay the groundwork for the visit, they dispatched Jason D. Greenblatt, a White House aide who has worked with Mr. Kushner on a Middle East peace initiative, and Avi Berkowitz, who works for Mr. Kushner.