The selection of Alaska Governor Palin was at first (and still) seen by many commentators as foremost, an effort to win over women disappointed over Hillary Clinton's defeat for the Democratic nomination, and her rejection by Obama as his VP choice, and secondly as a tactical way to quickly divert media attention (and news cycles) away from what they realized even before Obama's Thursday night speech would be an extremely successful Democratic convention. True, the McCain camp did pick Palin as bait to go fishing for female voters, and to see how many might bite, and even somewhat to reinforce his alleged "maverick" image with voters.
Nevertheless, it's a mistake to view these goals as the primary reason for the Palin pick (which makes the choice look like a huge gamble), rather than potential windfall bonuses, the success of which aren't essential for the pick to yield it's main payoff: the engagement and energization of the GOP base, especially the evangelical right. Their turnout was the crucial difference in Bush winning Ohio in 2004.
THE GOP IS GOING TO TRY TO TRANSFORM THIS INTO ANOTHER BASE ELECTION, LIKE 2004. A corollary part of this strategy is to turn this into a contest mainly between core bases, and try to turn off independents who are not at least strongly susceptible leaners their way. IT'LL GET MUCH UGLIER.
Here's a link to a PBS Frontline article about that strategy:
What was firmly driven home to McCain during his VP selection process was that much of the hard-core right wing might give insufficiently enthusiastic support to Romney or Pawlenty, and would outright rebel and stay home in droves if he picked Lieberman or Ridge. They wanted someone clearly one of their own, and with Palin, they got it. McCain has now secured his base, but at the cost of stirring some skeptical headwinds among independent (and only loosely aligned democratic or republican voters) by the Palin pick.
So: a core McCain strategy will be to attempt to turn off enough independents and newly registered voters who were initially attracted to Obama, with a viciously negative campaign, far more so than it's been so far. It will quickly become apparent that McCain is only hoping to win a modest portion of the independent vote; he's hoping to discourage most of the rest from turning out. It's going to get much, much, ugler yet - the GOP will float dozens of trial balloons until they fins something that sticks enough to distract the MSM for two-three days, then something else, then something else.
We've been there, done that - 2008 may bear a painful resemblance to 2004 before it's all over. UNLESS WE WORK VERY HARD TO KEEP THAT FROM HAPPENING.