Ferguson is actually in my opinion not the answer because he pushes a brand of politics that virtually everyone agrees is a liability for Democrats but seems to consider it worth it...a real Democratic hack would be lashing at weird gender neutral language and the like.
I'd go with wbrocks67 or Alben Barkley as the most partisan Democrats.
GMac is up there too by this metric.
He criticizes Democrats too much. Note that Alben Barkley doesn't really dump on Bernie Sanders (who is for all intents and purposes a Democrat), he just attacks vague woke activists and Twitter clowns.
This also disqualifies DrScholl who hates Bernie as much as he hates Republicans (and while not eligible due to nor being American Landslide Lyndon is amusingly worth a mention here too, imagine living in Greece and having an obsessive hateboner for Bernie Sanders while spending most of your online time compiling and reporting bad remarks from random Republicans.)
GMac is fanatically loyal to the concept of the Democratic Party as an institution. This hackishness extends beyond loyalty to any one person. For example, he’s obsessed with Hillary, but if she started to denigrate The Party I’m confident he’d immediately turn on her.
