"Progressive" was appropriated by the Stalinist-front organizations that mounted a rump convention of the lefty-trendy wing of the Democratic Party in 1948 to nominate Henry Wallace for President. George McGovern, the 1972 Democratic Party nominee, was a delegate to that "Progressive" convention in 1948.
The "Progressives" took over the Democratic Party in the 1970's and locked out the traditional Democrats from the decision-making processes. They have been identified with the "liberal wing" of the Dems ever since, although the word "liberal" is a misnomer when applied to "Progressives", who would better be called simply Communists. A few remaining liberals understand this distinction, but the voice of "liberalism" has long since been taken over by the "Progressives".
This is my thinking ever time the ads for Progressive Insurance run. The CEO of Progressive Insurance is a major “progressive” from what I have read.