I really don't see what Democrats' fascination with this guy is - not that I have anything against him, I just don't see what all the hullabaloo is with him.
It's because Schweitzer is a populist, and one of the few Democratic politicians that "speaks truth to power" and actually criticizes the GOP, instead of going "I wouldn't do that, but..."
Plus, his folksy persona and his support of gun rights is seen as very useful for winning or at least disputing traditional red states.
Personally, I like all of the above, plus his efforts to bring renewable energy and universal healthcare to his state.