According to the Politico, McCain is going to announce his Veep pick on August 29th,

Sen. John McCain (R-Ariz.) plans to celebrate his 72nd birthday on Aug. 29 by naming his running mate at a huge rally in the battleground state of Ohio, Republican sources said.

That's a week from Friday, and the day after his rival, Sen. Barack Obama of Illinois, accepts the Democratic nomination at a 70,000-person spectacular in a Denver stadium.

...Sources close to McCain say he has wrestled with the choice, torn between a high-stakes, high-reward pick like Ridge or Connecticut Sen. Joseph I. Lieberman -- the Democratic vice presidential nominee in 2000 -- or a safer and more conventional selection such as Romney or Pawlenty.

There are 3 questions you have to ask about those three men.

#1) Does a McCain/Romney ticket carry Michigan?
#2) Does a McCain/Pawlenty ticket carry Minnesota?
#3) Does a McCain/Lieberman ticket bring in enough moderates to replace the conservatives it will alienate?

Incidentally, #3 may be the most pertinent question at the moment given this news from the Corner,

NR has learned that the McCain campaign has been calling key state GOP officials around the country the last couple of days and sounding them out about the consequences of a pro-choice VP pick. The campaign is asking about the reaction of conservative grass-roots activists to such a pick and whether a pro-choicer can be sold to them. This is an indication that the McCain campaign is serious about the possibility of a pro-choice VP nominee and that McCain leaving the door open to Tom Ridge last week may not have been merely a friendly nod to a longtime supporter.

Lieberman is EXTREMELY liberal when he gets off of defense issues and I am not really sure it's a great idea to have a guy like that in the #2 slot when the head man is 72 years old.

As to Ridge, he's a squish, closely associated with the Bush Administration, not well liked by conservatives, and he's pro-abortion. Still, if he could carry Pennsylvania, McCain might have to consider him, but take that away and he'd be a real dud of a VP choice.

Honestly, I think that if this is really the batch it's down to (and who really knows), I'd go with Pawlenty because he's the only one who wouldn't rile up the Right. At this point, given that Obama and McCain are neck and neck, I don't think McCain needs to reopen wounds with conservatives by taking a VP who reminds them of why they didn't like him in the first place (and, yes, with segments of the GOP base, Mitt Romney would produce that same reaction). At this point, a "better safe than sorry" VP pick should beat a "high risk/high reward" selection for McCain.