Like other businesses, politics these days is conducted less in person than on speaker phone and laptops. Campaign consultants, policy analysts, fund-raisers and bloggers do most of their work in the comfort of their own homes, or in their cars, or maybe at Starbucks. Political professionals have as a result become part of a much larger American movement. In his new book, “Microtrends,” the Democratic pollster Mark Penn notes that 4.2 million Americans now work exclusively from home (a nearly 100 percent increase from 1990), while some 20 million do it part time. Some of these workers are employees who telecommute to traditional offices, but most represent a kind of modern, untethered American work force.