A Republican state Senate challenger claims he was harassed, sworn at and spit on before a campaign luncheon last week by backers of his Democratic incumbent opponent. Falmouth businessman Tim Duncan said the incident occurred outside a Plymouth country club, where he said 75 to 100 backers of Sen. Therese Murray (D-Plymouth) confronted him. ``People began rocking the car, spitting on the windshield and shouting profanities at me, my wife and children,'' Duncan said. Several in the crowd waved copies of a Falmouth building permit he had taken out, shouting, ``We know where you live,'' Duncan said. ``It was pretty...