*** “It’s just an environment of possible retribution,” Mr. Wood said. “It is that fear she instills.” Over nearly 30 years, Ms. Collins, a self-styled moderate in a familiar Maine mold, has cultivated a public persona as a workhorse and a fastidious maestro of constituent services and pork-barrel disbursements, using her Washington know-how to get her constituents what they need. But for just as long, her detractors say, she has managed to mostly mask another reality. “The gentlewoman from Maine,” as her colleagues say on the Senate floor, is a formidable power broker who can play a fierce brand of...