I'm not saying that the State Treasurer is a widely known position but don't make him out to be some fire-breathing unelectable nutcase. History proves you wrong.
Mourdock is mild mannered. Sure, the "bitterly partisan" stuff doesn't help but he isn't a far right winger and should be able to come across as a reasonable person/non-bomb thrower. That's enough for a win in an obviously Republican leaning state.
I'm not making him out to be an unelectable nutcase. I think there is a chance he could pull this off, simply by constantly trying to tie Donnelly to Obama. But he is not a good candidate - this should be a very easy win for the GOP, and it's not. If I had known this would have happened, looking back, I wish Lugar had backed out and Skillman had ran for this. We'd be fine.
I disagree with your assertion that he isn't a "far right winger", simply due to the fact I've watched his campaign, both for Treasurer and Senate, and have heard him speak several times. On issues, he's very conservative. He just doesn't make quite as many ridiculous statements as other far-right candidates do. I guess we'll just have to see how Indiana reacts to him - thankfully I'll have a frontrow seat of this interesting race unfolding.