If Democratic candidates ran on progressive ideas on a consistent basis...

[Recursion]

72. Good question. It's a term with a lot of baggage

It was originally used for New England Republicans, later for Southern Democrats (Strom Thurmond was a "progressive Democrat" when he fought back against including African Americans in the New Deal). In the irony of ironies, Hoover was the last President of the original "progressive era", and was swept out of power by FDR who ran against his (what was then called) Progressivism.

In its modern context it was re-coined by IIRC Carville and the evil scary DLC types like Bill Clinton to avoid some of the baggage that "liberal" had by the 1980s (which baggage was mostly racial -- it's been a term with a very unfortunate racial history, which is why I'm cautious about it). Carville subtitled his awesome 1996 book "We're Right, They're Wrong" as "A handbook for spirited progressives". At that point, the sense behind the term as best as I can make it out was the "it's the economy stupid" line: economic growth before anything else, social issues can come later (hence Clinton's waffling on gay rights and his Sister Souljah moment).

In the intervening two decades an interesting inversion has happened, though. White liberals disaffected with the growth-oriented economic policies of Clinton & co. have relabeled redistribution-focused economic politics married with strident social activism as "progressive". Meanwhile, the Clinton faction has seen which way the wind is blowing on race and gay rights, and now see those as wedge issues that are in our favor. So the self-styled "progressives" of the 1990s are now the "third way reactionaries" of the 2010s, and their main common ground is the social issues that the third way types were keen to avoid 20 years ago. (Other than gun control, which was pushed as a third way plan to appear tough on crime without significantly alienating exurban whites -- whatever else it's been, it hasn't turned out as that).