Mr. Sweeney, the second most powerful lawmaker in New Jersey and a Democrat, lost his bid for re-election to Edward Durr, a driver for a furniture chain. For nearly a decade, Stephen M. Sweeney, the second most powerful lawmaker in New Jersey, seemed truly unassailable. He boasted deep ties to the most feared political power broker in the state and unyielding support from the influential building trade unions. Four years ago, the state’s teachers’ union spent more than $5 million to unseat him. He won by 18 points. This year, his challenger was Edward Durr, a truck driver for Raymour...