There’s an interesting at RealClearPolitics on what you can learn by “text mining” State of the Union speeches. We learn that George W. Bush varied from right to center-right, Bill Clinton varied from left to center-left, and Barack Obama has been consistently left of center. You could have struck me dead with a feather.
I would make the distinction between rhetorical positioning and actual political ideology. The distinction is between what they say and what they do. So, for example, I think that George W. Bush was actually center-right, Bill Clinton’s only ideology is power, and Barack Obama is center-left although he may prove me wrong by his actions after the 2014 midterms.