NEWARK, N.J. (AP) — The news of Kamala Harris' sudden departure from the presidential race came during an all-staff conference call led from Cory Booker's campaign headquarters in Newark, the New Jersey city that he led for seven years and that propelled him to national fame. Within hours, Booker dictated a message calling Harris "my friend and my sister," and a directive was issued to show her team respect at a difficult moment.

The campaign also scheduled a high-profile speech in Iowa.

Booker's aides have been careful to emphasize that the New Jersey senator isn't looking to capitalize on th...