Santorum would be way too controversial of a pick. Picking this guy would be ten times worse than George Bush picking Dan Quayle as his VP. The media would parse every single comment he has made in the past 20 years that would even sound remotely un-PC. He was defeated in 2006 by a 20 point margin, so the former Senator from Pennsylvania doesn't exactly bring a lot of electoral prowess to the ticket. If McCain wants a conservative on the ticket, there are surely better options.