I will refrain from any “guess the VP” antics because it really is impossible to see through the spin. But without squinting to read the tea leaves, I have a few thoughts. First, I would imagine being a blabbermouth about your prospects is a negative thing and suggests problems (e.g. inexperience, message discipline). Second, for Barack Obama the hard thing is whether to compensate for his lack of experience or to deny that it is an issue. Many have commented that Tim Kaine lacks the same things Obama does –national security credentials, hard accomplishments, etc. — but by picking him Obama certainly wouldn’t risk putting someone on the ticket who might overshadow him and get tongues wagging. (“Well if experience is so darn important for a VP why not the President?”) So it is a tricky line to walk on the experience/national credentials front: make it better or make it more obvious.
For John McCain the problem seems more simple: who will do no harm? Don’t upset the base, but don’t freak out independents. It really isn’t so much a question of what the VP might add but what damage he might do. None of those in the VP running (from what we know) seem to have the ability to guarantee a state or a demographic group. At most they may help in a state (Michigan or Minnesota). But the key to McCain’s victory is not to take the country by storm in a spasm of excitement. He essentially must make the case that Obama shouldn’t be trusted with the presidency and is a political opportunist. So the watchwords for McCain: don’t make that harder, don’t create a distraction and don’t do anything to diminish his argument that his ticket is the one for governing in tough times. And if the press screams “Boring!” Well, that’s par for the course and not how the election is going to be won or lost.