It's pretty simple, really. McCain is trying to prove that he's a maverick.

[TwilightZone]

Let's not underestimate this choice. As shallow as a large portion of the electorate is, this isn't as poor a choice as it might appear.

[elocs]

1. Well, he's going to be a pseudo-maverick loser come November. n/t

[SteelPenguin]

2. It does strengthen his 'Maverick" cred

But it's not alot, and as long as we keep saying 90% of the time he voted with Bush, it sort of deflates anything he tries to put forward. Plus it obliterates his 'not ready to lead' schtick by picking a vp candidate with even less experience.