MANCHESTER, N.H. (AP) – Joe Biden was greeted with the respect that comes with being a former vice president when he took the stage at a New Hampshire Democratic convention. Some of his closest rivals were greeted like rock stars. The scene in New Hampshire highlights one of the riddles of Biden’s candidacy. He maintains a lead in nearly every poll, but his campaign often lacks the look and feel of a front-runner. His crowds are warm, but rarely high-energy. His organization is solid, but doesn’t always show up in force at key events that help shape the perceptions of political power brokers. Biden’s team insists such optics are overrated as indicators of a candidate’s strength, saying he is unique among Democrats because of a reservoir of goodwill from a broad group of supporters.