I'm pretty sure it will be Romney or Pawlenty. And Pawlenty's stock is on the rise at the moment. He could swing Minnesota, which might very well be the Republicans only pickup this year. He also has tons of personal synergy with McCain.
Romney is more of a shield against economic attacks. I don't think his second advertised purpose (unifying Republicans) would work as advertised. For one thing, he's a Mormon, (One of the few religious differences that still matter to some), and for another, he played Johnny come lately as the Savior of the conservative base (Version 1.0: Non Southern Fried Creationist Edition), before that he had to hide from hunters searching for RINO ivory. Oh, and by all accounts he an McCain hate each other, but that's incidental.
Bobby Jindal ls the wonder kid of the GOP, young, and more experience then most 60 year olds. Unfortunately the same Americans that think Obama is a flag burning Muslim can't tell the difference between him and the Indian kid behind the counter at 7-11. He hasn't quite imitated Sherman (Either in the speech, or in burning Savannah), but he seems pretty sure he won't be VP
Mike Huckabee, on the other hand, is beloved by the same people that hate Jindal, and he has a friendly, authentic personality. The problem is that a large part of that personality is insane. He's also a tad more economically liberal than the base would like, but that's an asset in this election
Sarah Palin is a national unknown, and share McCains basic political views (She points to something and flips a coin. Heads and she's a conservative, tails she's a moderate) She also meets Obama's black man and raises him a woman. As sad as it is, McCain might need her help to hold onto Alaska this year.
Charlie Crist would pretty much allow McCain to count on Florida, which is great. He's also a decent governor, and he and McCain like each other (No, not like that). On the other hand, Florida probably isn't that much of a worry for McCain (That's speaking as a Floridan). It's a decent territorial pick, but he isn't getting many references by the McCampain or the Media
Tom Ridge is essentially a Pennsylvanian version of Crist, tactically speaking, he has more experience (legislative and national security, and may move his state out of the Democrat's column.
Rob Portman is the third of the 'native son of a swing state' trio, and the only non governor. He could help McCain in Ohio, which is obviously critical. On the other hand he was part of Bush's trusted braintrust on economics.
Ouch.
