According to Time magazine, John McCain wanted Joe Lieberman for his vp, and his second choice was Tom Ridge. The Republican party "elders" vetoed both and that left McCain scrambling for a third pick with very little time to do it. He had not vetted Palin very well at all, obviously. He has many differences in opinion on major issues with her. The causes of global warming is one such area. Palin doesn't believe it's man-made at all, while McCain knows a lot of it is. The drilling in Alaska is another area, Palin for McCain against. Also, McCain is against spending money on "pork" projects like the bridge to nowhere, whereas Palin actively campaigned for money for that very bridge.