>I thought you were talking about classification of these tweets so that politicians know what their followers are talking about. Sentiment analysis is a very small part of what we do and as you said there are tons of examples on web that use Twitter's data in their model.

I was, I was guessing that you had an general topic/clause segmentation model + sentiment analysis, sounds like you're saying the topic/clause (or issue) segmentation model is pretty domain specific, so what new datasets you'd need to for political issues build is beyond me, but I think it'd be well worth it. Connecting politicians and constituents is a pretty universal need.