Why the McCain campaign picked Palin, I think, comes down to two (more tactical) reasons intertwined with one larger reason. First, the larger reason as set forth by LG&M:

[O]ne thing to take from picking Palin is that McCain's internal polling must be terrible. Just as Biden is a good frontrunner pick, Palin only makes sense if you think it's worth a considerable risk that your pick will be a complete catastrophe because with a safe pick you're going to lose anyway, so you might as well be "bold" and hope you catch lightning in a bottle. I'm not saying that's a good reason, but they can't be optimistic.

So, in other words, the Hail Mary pass.

Then there's the enthusiasm gap. Poll after poll has shown the Democratic base more enthused, excited, and happy about the Democratic nominee. The GOP base lags far behind. Palin is a bona fide Evangelical Christian conservative. Adamantly anti-choice, and a darling of sorts to Christian conservative activists. With the Palin pick, the McCain campaign's hope is to finally rally a base the campaign couldn't consolidate on its own.

Finally, there's the "PUMA" gambit. The idea is that there really are a lot of Clinton voters who now will most assuredly vote for McCain with a female vice presidential running mate. I seriously don't think there are a significant amount of this type of voter out there. I would think that the McCain campaign's pollsters don't think so either. Has the McCain campaign ceased to be honest with itself, and has come to believe its own spin as to a vast force of PUMA voters out there? Maybe. More likely, I think, is that the McCain campaign feels compelled to play to media perceptions and desires for PUMAs to exist in large numbers. It's a more interesting story, and it changes and obscures what would have been a weekend news cycle of Obama's wildly successful convention in Denver.

But for a campaign to saddle itself for the rest of the campaign with a readily apparent weak candidate does not seem worth it, given that this pick likely helps only in possibly winning a news cycle.

This is not a bold move. This is a desperate move.

... and did the McCain campaign even do a proper vetting of Governor Palin?