WASHINGTON — In early November, a few days after Senator Kamala Harris’s presidential campaign announced widespread layoffs and an intensified focus on Iowa, her senior aides gathered for a staff meeting at their Baltimore headquarters and pelted the campaign manager, Juan Rodriguez, with questions. What exactly was Ms. Harris’s new strategy? How much money and manpower could they put into Iowa? What would their presence be like in other early voting states? Sign Up For the Morning Briefing Newsletter Mr. Rodriguez offered general, tentative answers that didn’t satisfy the room, according to two campaign officials directly familiar with the conversation....