Speculation is in full throttle concerning who the candidates for president will choose as their vice-presidential running mates. Here is just one example.
Remember two things: first, all the speculating now doesn't mean a thing. The candidates won't choose anyone now, or even try to come to a decision now. They want the speculating to continue. Because that means attention is being paid to them, and attention is good for a campaign.
Second: history shows us that vice-presidential choices are largely all about who will help win the fall campaign. Keep that metric in mind when you try to predict who will be chosen.