Leading Democrats smiled just thinking about what it would mean to beat Trump with the first female president — a woman of color, a child of two immigrants, a prosecutor, and a candidate who talked about joy and offered up her smile against the scowl that had become his most common expression. Her candidacy sparked in them the unfamiliar feeling of hope. Harris’ team would have gladly taken more time to introduce the vice president to the country, or to put together an operation, which, after the ticket switch in July, woke up every morning at campaign headquarters and in the states feeling behind on planning.