Vice President Kamala Harris got off to a rocky start in office. She is now at the heart of a political drama that could make her the first woman of color to become a major party presidential nominee. Vice President Kamala Harris, who has struggled for nearly four years in President Biden’s shadow, was thrust on Sunday into the center of a remarkable political drama that could culminate with her becoming the first woman of color at the top of a major-party presidential ticket. Mr. Biden’s decision to abandon his re-election bid and endorse Ms. Harris to succeed him puts...