Former Mississippi Gov. Haley Barbour
North Carolina Sen. Richard Burr
Florida Gov. Charlie Crist
Former Arkansas Gov. and former presidential candidate Mike Huckabee
Utah Gov. Jon Huntsman Jr.
Texas Sen. Kay Bailey Hutchison
Minnesota Gov. Tim Pawlenty
Former Ohio Rep. and former Director of the Office of Management and Budget Rob Portman
Former Massachusetts Gov. and former presidential candidate Mitt Romney
Wisconsin Rep. Paul Ryan
South Carolina Gov. Mark Sanford
FedEx CEO Frederick Smith
GOPAC Chair Michael Steele
http://www.usnews.com/articles/news/campaign-2008/2008/04/04/mccains-potential-vice-presidential-candidates.html
I could see Barbour, Sanford or Pawlenty.