I don’t think it makes a ton of to try to evaluate presidential candidates in terms of how often they describe themselves as “progressive”. On the right, the term “conservative” has a pretty clear valence — if Candidate A is more conservative than Candidate B, then Candidate B is more moderate than Candidate A. “Progressive” is, among left of center people, a much more mixed bag of a term. Some people would use it to mean something like “John Edwards’ domestic policy is more progressive than Barack Obama’s,” meaning that its more ambitious, less respectful of elite CW about balanced budgets, etc.
On the other hand, when the DLC wanted to start a think tank they called it the Progressive Policy Institute. “Progressive” in this sense is meant to denote a Third Way approach and provide a contrast with the traditional “liberal” orientation of the Old Democrats or the “socialist” orientation of Old Labour.