Who is McCain's pick?

John McCain is scheduled to announce his running mate in just about two hours, but so far, no one seems to have any idea whom he has picked.

All morning, the likely candidates have been dropping like flies. It's not Mitt Romney. It's not Tim Pawlenty. It's not Joe Lieberman. It's not Mike Huckabee. Speculation early this morning focused on Alaska Gov. Sarah Palin, but her staff says she's in Alaska, not Dayton, Ohio, where McCain's rally will start at 12 p.m. Eastern. Fox News was reporting this morning that her aides can't actually say for sure where she is. (Given how well the campaign has guarded the pick, it's possible any of those denials could be wrong.) Republican sources tell Salon they haven't heard anything yet, though they're impressed by the secrecy involved.

McCain kept the search close to the vest all summer, consulting with a tight inner circle of aides who all refused, constantly, to talk about the process. In the past few days, reports indicated that even those aides didn't know whom McCain had picked. Political operatives thought Barack Obama's campaign did a good job keeping Joe Biden's name out of the news until the night before that famous text message went out, but McCain has clearly gone one better.

If it is Palin, it could make the "Obama's not ready" argument a little tougher to sell. At 44, she's younger than Obama, and she has been governor only since 2007. She's very conservative, but she ran on a reform platform and distanced herself from the scandal-plagued Alaska Republican establishment.