Progressivism started out Ross Perot style, picking up Democrats and Republicans. The Republican Party now has become pretty much the original Progressive Party with a mixture of left and right. The left started hijacking the progressive name in the 1960s. The left has a long history of assuming new brands to confuse the voters. Today there are even many Democrats hiding behind a Republican label. A nest of leftism can't survive the disinfectant effect of a few minutes of direct sunlight.
The use of the word “Progressive” as a euphemism for Socialist/Communist goes all the way back to the 30’s.
A very unfortunate choice of words for Miz Hillary, unless she meant it as a code phrase for the Far Left.