Why do Democrats label themselves Progressive?

[Sam Spade]

Democrats label themselves progressive nowadays because the term "liberal" has attained such a negative connotation.

As a historical note, in America, during the Cold War era, the term progressive was always used by members of Communist party and its various offshoots as a code word to refer to other members.  Just as an FYI (no, I am not claiming so-called progressives nowadays = Communists, just a first-hand knowledge I have ).