Kamala Harris, California’s Attorney General, Leaps to Forefront of Senate Race

When Kamala D. Harris, a Democrat, was the newly elected district attorney of San Francisco in 2004, she walked into a firestorm after deciding not to pursue the death penalty for a man accused in the killing of a police officer — drawing attacks from law enforcement leaders and even Senator Dianne Feinstein, one of the most respected Democrats in the state.

Six years later, when Ms. Harris ran for state attorney general, national Republicans poured more than $1 million into her race, trying to defeat her with charged advertisements...