For what it's worth, I talked to eight or so GOP operatives for my Pawlenty piece and brought up Lieberman's name almost every time. About half thought it was a lunatic idea, the other half thought it was a decent idea but still highly unlikely.Seems about right. McCain picking Lieberman would make the blogosphere go apeshit, no doubt about it, and I do worry that it would lend more of a seal of approval to McCain's "centrism". Lieberman is assuredly not a Democrat anymore, but the public no doubt still identifies him as such, and him being on McCain's ticket would be embarrassing.
On the other hand, the very GOP conservatives that McCain's not exactly wowing would be less than wowed at a pro-choice domestic policy moderate-to-liberal as the #2 choice, especially considering McCain's superannuated status.
So, it's a high-risk proposition. But if Obama's recent Florida lead keeps steady McCain might decide that the risk is worth it. He can't do the Rove strategy in this election--that only works when the GOP base is as big as the Democrats' and this election cycle it isn't. This is the first data point that makes me think that McCain might actually pick Joe Lieberman as VP.
Of course, McCain should keep in mind that it wasn't as though Lieberman's presence on the ticket last time won Florida for Al Gore...