Vice President Kamala Harris has been the White House's first line of defense after President Joe Biden's faltering performance in last week's debate with Donald Trump. At campaign events, she concedes that Biden didn't do well but emphasizes the stakes of the election as she tries to rally anxious Democrats. It's a delicate moment for Harris, who is the first woman, Black person and person of South Asian descent to serve as vice president. Harris’ work on Biden’s behalf could lead to a political dead end, or it could secure her future within the party by providing fresh opportunities to prove her doubters wrong.