John McCain has made up his mind about his VP pick and we will soon know much about the man by whom he chooses. Here's how I'll look at the choice:
If McCain picks Lieberman it means that he is feeling frisky and wants a major fight with the right side of his party at the convention and an all-out brawl wherein delegates swat Lieberman away ala Harriet Miers, will ensue.
If he picks Ridge it will be for the same reason-to show the Right who's in charge, and though the convention would be unlikely to reject the choice, it would probably mean not a few conservatives staying home in November.
If he picks Romney, he will have calculated that Evangelicals, freaked out by his Mormonism and who might stay home would only lower his totals in red states that he'd win anyway, and that this would be offset by the fact that he'd pick up Michigan, maybe even Massachusetts and a lot of Mormon campaign money.
If he picks Pawlenty, he's thinking long term, wanting to leave a legacy behind after he's gone, by picking a young, relatively malleable guy who is conservative enough and will carry McCainism (whatever that is) into the future. He may also pick up MN's electoral votes.
If he picks Kay Bailey Hutchison it will be a bold play for disenfranchised Hillary voters and conservatives are unlikely to holler too loud since despite her pro-choice rhetoric, her voting record has been pretty solidly anti-abortion.