A few things which occur to me as strong positives for Mitt Romney's possibly choosing Paul Ryan as his running mate:
- We've already seen Ryan have a complete mastery of budget items, and the ability to completely demolish Obamacare. Ryan can erase the charge against Romney that he doesn't have specifics in his plan, and erase the (ridiculous) charge that Romney will be even slightly sympathetic to Obamacare.
- Given Ryan's working-class background and his success in a working-class, Democrat-majority district, Democrats will find it harder to paint Romney as simply a tool of the rich.
- He's Catholic, and that could be important in Pennsylvania, Ohio, and perhaps Ryan's home state of Wisconsin
- Perhaps most importantly, while I don't know Mitt Romney, I do know Paul Ryan a bit and I can see how Romney would feel very comfortable with Ryan who is fairly soft-spoken even when offering an intense message, and is always friendly and polite -- a description which roughly matches what I've seen of Romney.