Unlike me some of you seem to think that the VP choice matters a great deal, so out of curiosity which Republican governor or senator would be the worst possible VP choice for Romney? Would there be a candidate, that could cost him 10%?
Among governors or senators? Probably not. Tom Coburn or Rand Paul might come close.
Basically a VP pick is irrelevant unless it makes some people question the candidate's sanity and good judgment (not counting partisans of the other side that were already convinced that such sanity was questionable, obviously). Eagleton being the textbook example, though other picks - Dan Quayle! - have had much more minor but effectively similar effects.
Even then, much depends on the media response. I mean, Republicans got away with picking Dick Cheney and Sarah Palin recently with no ill effects.
I don't think you can
win votes with a VP pick, though there will be hacks that do think so.
Thankfully West is neither a Governor nor a Senator. And as to the literal "Worst Possible VP for Romney"... I think a random 35-year old Black homeless person with mental problems and a few felony convictions would be an even worse pick than West.