Turnout looked pretty low across the board didn't it? W got over 62,000,000 votes himself in 2004...
The overall turnout is always higher in a presidential election year than it is in a midterm year. The turnout of the base is buried and takes a significant amount of work to extract. Those numbers are never reported. As far as the 62M+ votes W got goes, that includes those that were swayed to vote for him.